^'i-OCHSSlNG-GNI Lpl-D17B U.B.C. LIBRARY ^um^^ ^i^ummm /f GREENHOUSES THEIR CONSTRUCTION and EQUIPMENT By W. J. WRIGHT, Director, New York State School of Agriculture at Alfred University. Formerly Assist- ant Professor of Horticulture at the Pennsylvania State College ILLUSTRATED NEW YORK ORANGE JUDD COMPANY LONDON KEGAN PAUL, TRENCH, TRUBNER & CO., Limited 19 17 Copyright, 1917, by ORANGE JUDD COMPANY All Rights Reserved Entered at Stationers' Hall Londp»^ Ei^Jatid Printed in U. S, A. TO MY FATHER IN WHOSE FLUE-HEATED, SHED ROOF PROPAGATING HOUSE I FIRST LEARNED TO LOVE THE SMELL OF THE SOIL PREFACE In 1912 the author was asked to present a paper before the National Vegetable Grow- ers' Association on the construction and equipment of greenhouses, with special refer- ence to the vegetable forcing industry. Much of the data given in this paper had been hitherto unavailable and was based on an extensive personal survey of greenhouse owners and operators, supplemented by per- sonal experience and observation. So great has been the demand for this data that at the request of the Orange Judd Company, the author has undertaken to incorporate it in book form. The present volume attempts a more thorough discussion of the subject than could be given in a single paper. It is based upon a series of lectures given be- fore the author's classes. This is the second book, dealing exclu- sively with this subject, which has been pub- lished in the United States. The former, written by Prof. L. R. Taft and published by vi PREFACE the Orange Judd Company in 1893, has been the standard and only work devoted entirely to greenhouse construction as adapted to American conditions. To this and to Pro- fessor Taft the author of the present volume is deeply indebted. It is not intended that this second book shall supersede the former but that it shall supplement it and emphasize present-day features. Probably in no line of horticulture has so great progress been made in the past quarter of a century as in floricul- ture and vegetable forcing. The develop- ment of the forcing house has been no less rapid. No attempt has been made to discuss the question of greenhouse construction from the standpoint of the manufacturer, although due credit must be given to the energy and ingenuity v^hich he has displayed in meeting the rapidly changing conditions and in the excellence of present-day construction. It is probably not too much to say, that the development of the flower and vegetable forcing industry has been largely dependent upon the improvement which has been made in the manufacture of greenhouse material and equipment. The real purpose of the book is to pre- PREFACE vii sent to the reader such information con- cerning the location, adaptation, general con- struction and equipment of greenhouses as will enable him to decide upon the type of house best adapted to his special needs; to supervise or assist if need be in its construc- tion or erection; to arrive at some conclu- sion as to the equipment most likely to ren- der the service required, and the probable cost. A special effort has been made to make the volume of service to the present owner of a greenhouse and to those who may con- template building, whether it be a small private house or a large commercial range. The arrangement of topics is made with reference to a pedagogical system which it is. hoped will be of service to the teacher and student. It is practically impossible to give in- dividual credit for all the sources drawn up- on in the preparation -of this volume. Spec- ial mention should be made, however, of the assistance given by the manufacturers of greenhouse building material and for the many excellent illustrations which they have furnished. When practicable, the source of these illustrations is given. Free use has also been made of bulletins of the various viii PREFACE Experiment Stations and of the United States Department of Agriculture. The book is offered with a full conscious- ness of its shortcomings, but with the hope that it may be of some definite service and that it may serve as a focusing point for criticisms and suggestions, out of which may be born a fuller knowledge through the experience and observation of its readers. W. J. Wright. New York State School of Agriculture, 1917, Alfred, New York. CONTENTS CHAPTER' I A General Survey 1-0 Classes of sash-beds — Classes of green- houses— Evolution of the greenhouse. CHAPTER H Sash-bed Construction .... 10-34 Hotbeds, location of, sash, pit, manure for — Coldframes — Cold or storage pits — Forcing boxes — Gable roof sash-beds — IMa^ts and shutters — Care of sash-bed materials. CHAPTER III Greenhouse Proper — General Con- siderations 35-49 Location — Arrangement — Size of houses — Pitch of roof — Measuring the pitch — Length of rafters. CHAPTER IV Greenhouse Architecture . . . 50-62 Lean-to or shed-roof houses — Even-span or span-roof houses — Uneven span houses — Ridge-and-furrow houses — ^Side hill houses — Curved roof houses — Curved cave houses — Circular houses. CHAPTER \^ Structural Material 63-79 Glazing sill — Eave plate — Gutter — Glazing bars — Side posts — Sash bars — Gable bars — Drip gutters — Purlins — Ridge — Kinds of wood used — Framing. ix X CONTENTS CHAPTER VI Framework, Methods of Erecting . . 80-96 Cardinal virtues of a good greenhouse frame- work— Foundations and walls — Wood-frame houses — Semi-iron *frame houses — All-metal frame houses. CHAPTER Vn Glazing and Painting 97-120 Greenhouse glazing an art — Glass to use — Size of glass — Lapped glazing — Butted glaz- ing— Putty — Setting the glass — How to esti- mate putty — Glazing points — Precautions — Liquid putty — Substitutes for glass — Kind of paint — Amount of paint required — Shading — Glazing ladder. CHAPTER VHI Ventilation and Ventilating Machinery 121-141 Systems of greenhouse ventilation — Side ventilation — Overhead ventilation — ^Size of ventilators — Hanging ventilator sash — Venti- lator operating machinery — Shafting — Shaft hangers — Gearing — Ventilator arms — Capa- city of ventilating apparatus — Sliding shaft system. CHAPTER IX Beds, Benches AND Walks .... 142-357 Advantages and disadvantages of benches — .Raised beds — Wood benches — Iron frame benches — Concrete benches — Height and width of benches — Arrangement of benches and walks — Walks and curbs. CHAPTER X Greenhouse Heating 158-166 The principles of greenhouse heatino;. — Heat- ing with flues — Hot water vs. steam heating — Combination heating systems — Heating coils — Cast iron and wrought iron pipes for heating. CHAPTER XI Hot Water Installation .... 167-187 General principles — Formula for determin- ing velocity of water in heating systems — Estimating radiation — Amount of pipe re- quired— Size of flow pipe — Length of coils — Exp^tnsion tank — Pressure systems. CONTEXTS xi CHAPTER XII Steam Installation 188-199 General principles — Size and length of coils — Size of supply and return pipes — Valves — High pressure steam heating — Vacuum and vapor systems — Arrangement of boilers — Steam pumps and steam traps. CHAPTER XIII Boilers, Fuels and Flues .... 200-225 Essentials of a boiler — Grate surface — Fire surface — Types of boilers — Cast and wrought iron boilers — Styles of cast iron boilers — Styles of wrought iron boilers — Steam and hot-water boilers — Boilers for burning hard and soft coal — Under-fed boilers — Self-stok- ing boilers — Size of chimneys and flues — ■ Arrangement of flues. CHAPTER XIV Water Supply and Irrigation . . . 226-241 Amount of water required — Types of pumps — Capacity of pumps — Power required — Hydraulic rams — Capacity of rams — Wind- mills for pumping — Storage tanks — Capacity of storage tanks — Overhead irrigation — Sub-irrigation. CHAPTER XV Concrete Construction .... 242-256 How concrete is made — Kind of sand re- quired— Kind of stone or gravel required — Crushed stone — How materials are propor- tioned— Directions for mixing — Amount of water required — Estimating materials — Forms for walls — Reinforcing — Walks and floors — Water-proofing — Concrete blocks — Cost of concrete work. CHAPTER XVI Plans and Estimates 257-262 Basis of estimate — Average costs — Detailed estimates — Information required in obtain- ing estimates. LIST OF ILLUSTRATIONS PAGE Conservatories, New» York Botanical Gardens Frontispiece 1 Hotbed in operation ...... 10 2 Standard hotbed sash ...... 12 3 Double-glass sash ...... 15 4 Plan" for permanent hotbed . . . .19 5 Permanent hotbed of concrete with cast-iron sills 19 6 Plan for temporary hotbed . . . . .20 7 Type of hotbed used when a large amount of heat is required ...... 20 8 Usual type of concrete hotbed . . . .21 9 Hotbed arranged for heating by flues . . 23 10 A good type of coldframe . . . . .24 11 Coldframe with sash removed . . . .25 12 A cold or storage-pit . . . . . .26 13 Sash-bed attached to basement of dwelling . 28 14 Types of forcing boxes or plant forcers . . 29 15 Forcing boxes in use on a commercial scale . 29 16 Gable-roof sash-bed heated by manure . . 30 17 Rye straw mats rolled for storage . . .31 18 Hotbed covered with mat and shutter . . .32 19 Private range of C. E. Chapman, Oakdale, N. J. . 37 20 Ground plan of range shown in Fig. 19 . .38 21 Commercial range of Hoerber Bros., DesPlaines, 111 . .39 22 Ground plan of range shown in Fig. 21 . .40 23 Part of vegetable forcing range of Searls Bros., Toledo, Ohio . . . ... .41 24 Diagram showing method of mea^suring pitch of roof ^ . . .42 25 Commercial range of C. FI. Metcalfe, Milford, Mass " . . .43 26 Diagram showing how heat and light rays are lost by reflection . . . . . .44 26a Diagram showing pitch of roof necessary to pre- sent an angle of 90 degrees to fhe sun's rays in winter . . . . ... . .45 27 An uneven span greenhouse . . . .53 28 Uneven span, side-hill vegetable house . . 55 xiii xiv LIST OF ILLUSTRATIONS PAGE 29 Ridge-and-furrow houses wrecked by a storm . 57 30 Diagram showing that the same amount of roof is required for several small, connected houses as for one large house covering the same area 58 31 Diagram of side-hill range . . . . .60 32 Curved-eave and circular types of construction . 61 33 Two methods of framing a semi-iron frame greenhouse ....... 64 34 Types of sills 65 35 Types of eave plates . . . . ,. .66 36 Types of gutters . . . . . .67 37 Type of gutter for curved-eave houses . . 68 38 Cross section of corner bar . . , .68 39 Types of wood sash bars . . . . .70 40 Two types of patented metal sash bars . . 71 41 King ''Channel Bars" 72 42 "U-Bar" type of sash bar 72 43 Gable rafter 73 44 Combination eave plate and gutter . . .73 45 Pipe strap for fastening sash bars to purlins . 75 46 "Pecky" cypress ...... 77 47 The concentric system of construction . . 78 48 A,^type of all-metal flat rafter construction . 81 49 Plan for an all-wood frame greenhouse . . 85 50 Two methods of framing a semi-iron frame house ........ 89 51 Structural steel post with board wall . . .90 52 Section of truss-trame greenhouse . . .91 53 Section of combination truss-frame greenhouse 92 54 Method of erecting a large combination truss- frame greenhouse . . . . . .93 55 Side view of house shown in Fig. 54 . . .95 56 A method of erecting small all-metal frame houses ........ 96 57 Lapped glazing ....... 102 58 Putty knife . 104 59 Machine for distributing putty .... 104 60 A. window glazing; B, greenhouse glazing . . 105 61 Putty bulb . _ 108 62 Types of glazing points ..... 109 63 Glazing with double pointed glazing points . 110 64 Glazing with single glazing points . . . Ill 65 Glazing ladder used in glazing and painting . 120 66 Greenhouse showing A. side ventilators; B, over- head or roof ventilators ..... 123 67 Method of under-bench ventilation . - . 125 68 Two methods of hanging ventilator sash . . 127 LIST OF ILLUSTRATIONS xv PAGE 69 Malleable iron shaft coupling .... 129 70 Shaft hangers . . . . ' . . .130 71 Open column ventilator gearing . . . 131 72 Open column chain operated ventilator gearing 131 73 Closed column ventilator gearing . . . 132 74 Chain system of operating ventilators . . 133 75 Rack-and-pinion system of operating ventilators ,133 76 Ventilators operated by means of rods with uni- versal joints ....... 135 77 Device for operating side ventilat9rs . . . 136 78 Compact machine for operating side ventilators 137 79 Types of ventilator arms ..... 138 80 Sliding shaft system for operating ventilators . 141 81 Cucumbers growing in ground, no benches used. 143 82 Tomatoes growing in solid raised beds . . 145 83 Solid raised beds of hollow building tile . . 145 84 Two types of wood benches .... 147 85 A type of iron frame bench .... 148 86 Greenhouse bench of concrete .... 150 87 Method of arranging benches in an uneven span house ........ 153 88 An arrangement of benches in a 30 foot house . 154 89 Another arrangement of benches in a 30 foot house ........ 155 90 A combination steam and hot water heating system ........ 162 91 Under bench heating with large cast iron pipes . 165 92 Diagram showing "down hill" and "up hill" sys- tems of hot water piping . .... 170 93 A type of automatic air valve .... 171 94 A method of piping a medium size house . . 178 95 Diagram showing under-bench method of hot water piping ....... 179 96 Gasoline engine arranged to circulate hot water in a greenhouse heating system . . , 180 97 Automatic expansion tank ...... 182 98 A type of mercury "generator" .... 185 99 A corner coil 191 100 A mortise coil 192 101 Reducing valve ....... 195 102 A type of steam return trap .... 199 103 A type of "vertical" or "square" sectional boiler 204 104 End view of "square" sectional boiler showing fire travel 205 105 Side view of "square" sectional boiler showing fire travel 206 106 Battery of five cast iron sectional boilers . . 207 I xvi LIST OF ILLUSTRATIONS PAGE 107 A t3-pe of "round" or ''horizoQtal" sectional boiler 208 108 Corrugated fire box boiler ..... 209 109 Type of tubular boiler much used in greenhouse heating 210 110 Battery of two marine type boilers used in green- house heating . . . . . .211 111 Wrought iron boiler without flues . . . 212 112 Sectional view of boiler shown in Fig. Ill . . 213 113 Altitude guage 215 114 Water column and guage ..... 216 115 Steam guage ....... 217 116 Diagram of automatic damper regulator . . 217 117 Asbestos pipe covering ..... 218 118 Boiler equipped for using natural gas . . 219 119 Chimneys should extend above the roofs of ad- jacent buildings . . . * . . . 224 120 Pumping jack ....... 227 121 Diagram showing installation of auto-pneu- matic pump ....... 228 122 A simple type of hydraulic ram .... 232 123 Plan for installing a hydraulic ram . . . 233 124 Overhead' irrigation ...... 239 125 A type of nozzle used in overhead irrigation . 240 126 Greenhouse bench arranged for sub-irrigation . 241 127 Proportions of cement, sand and stone required to form concrete ...... 245 128 Form for a concrete wall ..... 250 129 Method of facing a concrete wall . . . 251 130 Structure of a concrete walk . ' . . . 253 131 A small power m.achine for mixing concrete . 255 GREENHOUSES CHAPTER I A GENERAL SURVEY It is not the purpose of this book to furnish detailed information concerning the manu- facture of greenhouse building material, for the cutting and shaping of the materials is the work of the mill and the factory. Its purpose is rather to present such informa- tion concerning the location, adaptation, erection and equipment of greenhouses as will enable the reader to decide upon the type of house best adapted to his special needs; to supervise or assist if need be, in its construc- tion or erection; and to arrive at some con- clusion as to the equipment most likely to render the service required. Greenhouses are the result of an attempt on the part of man to create conditions favor- able to the growth of plants in climates or during seasons naturally unfavorable. They must, therefore, protect the plants from cold and storms, allow for an abundance of direct sunlight, provide for ventilation and in most 1 2 ■ GREENHOUSES cases they must be equipped with facihties for artificial heating. In a general sense, the term greenhouse re- fers to those glass structures used for the growing of plants. They are for the most part above ground and are house-like in ap- pearance. There is, however, another gener- al class of glass structures also used for the growing of plants but which are low and often almost wholly under ground. Unfor- tunately, there is no general term commonly applied to them as a class, but since it is common to use in their construction certain standard-size glass sash, the author ventures to suggest the term sash-bed as a general one to include structures of this class; and it is so used in this book. CLASSES OF SASH-BEDS* Hotbeds. — These are low structures, being almost wholly under ground, but having a glass roof made up of sash which are of con- venient size to be lifted off, so that the grow- er may care for the plants. They are usually warmed by the heat generated by decaying vegetable matter, commonly horse manure. *For details see Chaptef II. A GENERAL SURVEY 3 Their chief use is for starting plants in early spring. Coldframes. — These are similar to hotbeds but are seldom heated and may therefore be of more shallow construction, as no pit is needed to store the manure. Their chief use is for the growing and protection of young plants after they have been started in hot- beds or forcing houses, or for the growing of plants in late spring after danger of severe weather has passed. Coldpits. — These are deep pits chiefly used for the storing of bulbs and semi-hardy plants during the winter. They are usually provided with sash roofs the same as hot- beds and coldframes, so that light may be ad- mitted when desired. CLASSES OF GREEN-HOUSES Forcing Houses. — These are greenhouses used for growing or "forcing" plants at other times than at their natural seasons. Prac- tically all houses used by commercial florists and vegetable growers are forcing houses. Conservatories. — In this class of green- houses, plants are kept mostly for display. Often it is not desired that the plants so kept 4 GREENHOUSES shall grow rapidly, but that they shall merely live. Often also they house for the most part such semi-hardy evergreen and other ornamental plants as may be grown outside during the summer. Such houses are com- mon in parks and private estates. They are usually ornamental in character, often with curved roofs, and present a lively contrast to the severe simplicity of the commercial forc- ing houses. Propagating Houses. — These houses are devoted principally to the propagation or starting of plants, especially those grown from cuttings. As cuttings require little direct sunlight, these houses are often erected on the shady (north) side of other green- houses or in out-of-the-way places. They should be equipped with benches, underneath which the heating pipes should be placed to furnish "bottom heat.'' The term hothouse, as commonly used, is a general term synonymous wnth greenhouse, and may be applied to any of the above classes. The term stove house is an old one, orio:in- ally applied to any greenhouse used for tropi- A GENERAL SURVEY 6 cal plants and thus of necessity kept at a high temperature. The use of this term is more common in England than in this country. A RANGE of greenhouses implies several houses more or less closely connected and under one management. The individual houses may be of any one of the classes men- tioned above or a combination of two or more classes. Such houses are often spoken of as a RANGE OF GLASS. A range of forcing houses is sometimes spoken of as a battery, and a range of sash- beds as a NEST. EVOLUTION OF THE GREENHOUSE It is said that the Romans, even before the time of Christ, possessed some knowledge of the forcing of fruits and vegetables, and util- ized for this purpose pits covered with slabs of a transparent mineral. Heat was supplied by fermenting manure, and occasionally by furnaces of masonry in which a slow fire of wood or dried manure was kept burning. How successful they were we do not know; but it seems certain that if any degree of perfection was obtained, it was because of the skill of the gardener rather than because of any special merit of the forcing pits. 6 GREENHOUSES Forcing houses seem to have had their origin in an attempt to grow in the northern countries of Europe fruits such as the orange and grape, which were grown to such perfec- tion in the countries to the south. Thus in England the grape vine is hardy, but the summers are too cool and the seasons too short to ripen the fruit to perfection. This led to the training of the vines on the south side of buildings and walls that they might receive more fully the light and heat of the sun. Later there was conceived the possibil- ity of still further protecting them by the use of glass sash leaned against the wall. From this it was an easy step to the building of a rather permanent framework close to the walls, on which glass sash were placed when required, forming a closed house. Sometimes the walls were made hollow and slow fires built within them to give additional heat. Finally the idea of heating the air instead of the walls on which the vines were trained resulted in the building of brick and stone stoves or fireplaces within the glass enclos- ures. These houses were never intended for winter use, but simply to make the summer and fall conditions similar to those farther south. A GENERAL SURVEY 7 The attempt to grow the orange in these northern chmates presented a different prob- lem because the trees had to be protected during the winter. This resulted in the build- ing of framework structures which were covered during the winter with wooden shut- ters and heated by means of a stone fireplace. There was little or no glass used, but the shutters were removed during the summer, leaving nothing but the framework to ob- struct the light and heat of the sun. A house of this description, built early in the 17th century by one Solomon de Gaus at Heidel- berg, Germany, is said to have been 32 feet wide and some 400 feet long, and to have sheltered 400 orange trees. The next decisive step in the evolution of the modern greenhouse seems to have been a combination of the two preceding types, de- signed for the growing of plants during the winter. They were permanent buildings having opaque roofs and high side walls, resembling dwelling houses, except that they were well supplied with side windows. At this time it was thought necessary to have opaque roofs to prevent freezing, and it became common to have a second story, which was used as a dwelling by the garden- 8 GREENHOUSES er, in order to prevent the heat from escaping or the frost from "entering" through the roof. It was not until the early part of the 1 8th century that glass roofs were found to be practicable, and they were even then slow in coming into use. The first greenhouses in this country sug- gestive of the modern forcing house came in- to existence toward the close of the i8th cen- tury. For the most part they were narrow houses of the shed-roof type, having a solid wall to the north and a glass roof sloping to the south. ^ They were warmed by flues, usually of brick, passing through the entire length of the house, and connected with a brick fireplace at one end and a chimney at the other. Following this, there came in rapid succession, improvements in form and methods of construction and especially in heating, both steam and hot water, being used early in the 19th century. The real progress in greenhouse construc- tion in this country came with the industrial development of the country after the Civil War. The United States census reports show that there was but one commercial green- house prior to 1800; only three prior to 1820, { A GENERAL SURVEY 9 and only 178 in i860. It was not until 1890 that greenhouses had assumed sufficient im- portance to secure a place in the census re- ports. At that time there were 4,659 estab- lishments covering 38,823,247 square feet, valued at $38,355,722. The following table shows the total num- ber of square feet under glass in the United States and ten principal states, as shown in the census reports for 1910, 1900 and 1890. The rank of the states has changed material- ly during the past 30 years. AREA UNDER GLuVSS IN THE UNITED STATES AND TEN PRINCIPAL STATES. FROM CENSUS REPORTS 1910 1900 1890 Tot. Glass Greenh'ses Tot. Glass Greenh'ses* Tot. Glass sq. ft sq. ft. sq. ft. sq. ft. sq. ft. U.S. 114,665,276 105,165,730 96,230,420 80,544,862 38,823,276 111. 15,950,853 14,380,857 8,744,020 7,318,744 3,236,750 N. Y. 15,066,587 13,878,875 13,635,440 11,412,863 6,947,289 Penn. 13,846,672 12,887,672 11,819,610 9,893,013 6,066,144 N. J. 8,840,511 7,984,752 11,190,250 9,356,283 3,703,554 Ohio 7,583,562 7,091,976 7,970,190 6,471,049 2,785,192 Mass. 7,382,009 6,817,585 8.710,280 7,290,504 2,717,946 Cal. 5,087,132 4,422,423 1,572,480 1.316,165 Mich. 4,122,099 3.922,772 2.593,230 2,170,233 1,293,44.> Mo. 2,812,221 2,545,138 3,126,400 2,616,786 1,240.00? Iowa 2,183,182 1,870,840 1,436,260 1,202,149 Ky. 1,163.241 Conn. 1,060,920 •Estimated. CHAPTER II SASH-BED CONSTRUCTION HOTBEDS As stated in the preceding chapter, hot- beds are low structures almost wholly under- Fig. 1. — Hotbed in operation ground, but having a glass roof made up of sash. They are usually heated by ferment- ing horse manure placed in the bottom, but may be heated by brick or tile flues, or by steam or hot water. Their chief commercial use in for the starting of early vegetable and flowering plants. In the home garden they may be used for growing to maturity in early spring or late autumn, such semi-hardy and 10 SASH-BED CONSTRUCTION 11 quick maturing vegetables as radishes and lettuce, and thus extend the season for sev- eral weeks or even months. They may also be used for starting and protecting early in the season, other slower growing crops such as melons, which are not transplanted but are allowed to mature in the beds. A gain of several weeks may thus be secured in the time of ripening. Well constructed and pro- tected hotbeds will withstand a temperature as low as zero if it is of short duration. Location. — The location for the hotbed should be (i) relatively high; (2) well drain- ed; (3) exposed to the sun throughout the day; (4) protected from north and north- west winds; and (5) either comparatively level, or sloping toward the south or south- west. For convenience it should be near some building which may be used as a work- room, and should be close to a supply of water. The south side of a building is often an ideal location, although there is some dan- ger, if the building be a light colored one, that the hotbed may become overheated. Sash. — Standard hotbed sash are 3x6 feet, and from 1% to I'^/s inches thick, the latter being more durable but heavier to 12 GREENHOUSES handle. Since they are subjected to especial- ly rough usage, they must be well construct- ed of good material, and must be kept well painted. Well constructed sash may be se- cured from any reliable dealer in greenhouse 'f =--rs?-:=:^=----='^s>,£aa„a 1 "' 1 1. ri 1 1 I'll 1 1 1- A B Fig. 2, — Standard Hotbed Sash A, three run sash; B, four run sash; C; Horned sash; X, iron rod to keep sash from spreading material. They may be of either cypress or ced^r and have mortise and tenon joints, though' the tenons should not extend quite through the bars, or they will be more likely to absorb moisture and thus decay rapidly. All joints should be painted with thick lead paint and should be put together while the paint is green. Sash with a light iron rod or bar across the middle, connecting the side SASH-BED CONSTRUCTION 13 bars, will usually prove to be more durable, as the rod prevents the sides from spreading. Most hotbed sash consist of three rows of glass so laid that the water will flow length- wise of the sash. For this purpose i8 panes of lo X i2-inch glass are required. Sash hav- ing four rows of glass are not uncommon, but the extra bar and laps obstruct so much light that they are less satisfactory, and they are rapidly going out of use. They require 28 panes of 8 x lo-inch glass. Sash may be purchased either glazed or unglazed. When time is plentiful and the workman is handy with tools, they may be glazed at home at a considerable saving in cost. Well made sash may be had, unglazed and unpainted, at from $1 to $1.25 each. The same sash glazed and painted cost from $3 to $3.50 at the factory. The price of glass varies greatly from year to year, but on the average will cost from 75 cents to $1 per «ash. Roughly speaking, the sash, putty and* paint will cost about $2.25, leaving from 75 cents to $1.25 for the labor of glazing and painting. Sash of varying sizes are sometimes seen, but their use is not advised. It is seldom possible to replace them as cheaply as when standard size sash are used. 14 GREENHOUSES When sash are glazed at home they should first be primed with a coat of lead paint. On looking them over it will be observed that one of the end bars is not so thick as the other, the upper surface being in line with the bottoms of the grooves or channels made to receive the glass. This is the lower end of the sash and should always be placed toward the southjs The glazing also begins at this end. In glazing, the first pane is laid flat, the bottom of the second lapped over the top of the first and so on, small brads or glazing points being placed at the lower end of each pane and along the sides to hold them in place. Since the lap obstructs the light it should be as narrow as possible, an eighth of an inch being as wide as necessary. In order to obviate the necessity of cutting the last glass to keep the laps even, it is well to lay all the panes for one row on loosely, and to space them before fastening any. They should then be puttied the same as ordinary windows, and thoroughly painted. A more satisfactory way of setting the glass is to bed them in putty as described in Chapter ATI, but this method is rarely used with hotbed sash. Sometimes the glass are butted; that is, they are laid flat, end to end, SASH-BED CONSTRUCTION 15 instead of lapped. This is rarely satisfactory for hotbed sash; because (i) the panes are often not squarely cut and do not fit well, and (2) the sash have so little pitch or slant when in use that water is apt to run through be- tween the panes. Some makers offer a form of sash known as ^'horned sash," in which the side bars ex- tend two or three inches beyond the end bars. These extensions make convenient handles for carrying, and it is claimed that a better joint can be made than when they are cut off flush with the end bars. Double-glass Sash, as the name implies, are constructed with two layers of glass with an air space of about a half-inch between. They have certain advantages over single- glass sash which may be stated as follows : (i) They give greater protection; (2) they reduce labor, as it is not necessary to use Fig. 3. — Double Glass Sash 16 GREENHOUSES mats as late in the season; (3) In moderate climates no mats or supplementary protec- tion IS needed; (4) the plants receive sun- light during the entire day when mats are not used, whereas, with single glass sash, the mats have to be left on until the sun is well up and then have to be replaced be- fore sundown. On the other hand, they have several dis- advantages: (i) The first cost is often as much as 50 per cent, greater; (2) they are heavier to handle; (3) they reduce the amount of light, especially if the glass be- comes loosened so that dust accumulates between the layers ; and (4) some users com- plain that they are short-lived because moist- ure collects between the layers and promotes rapid decay. The most enthusiastic supporters of these sash are those who live in climates where this type of sash never need supplementary protection, but where it is not safe to leave single-light sash unprotected. It is but fair to state, however, that their use is rapidly in- creasing, even in the north. Temporary Sash, made of oiled paper or treated cloth, are sometimes used for special SASH-BED CONSTRUCTION 17 purposes and give more or less satisfactory results. Directions for making will be found in Chapter VII. The Pit. — As most hotbeds are heated by fermenting manure, a necessary part is a pit of some depth in which it may be placed. This pit may be lined with boards, plank, brick, stone or concrete, the latter being the most satisfactory. Cypress, cedar, chestnut and black locust are the most durable, moder- ate price woods for this purpose. For data on concrete construction see Chapter XV. The depth of the pit is determined by: (i) The severity of the climate and (2) the kind of plants to be grown. As more heat is pro- duced for a longer time from a deep pit of manure than from a shallow one, it is evident that in cold climates and for plants requir- ing considerable heat, such as tomatoes and peppers, the pit must be deeper than in warmer climates, or for plants like cabbage or cauliflower which may be grown at lower temperatures. For starting early vegetable plants in late February or early March in the north, 24 inches of manure will be re- quired, whereas in milder climates, or later in the season, 12 to 18 inches will be suffi- 18 GREENHOUSES cient. The manure will continue to give off heat for three to six weeks. The dimensions are determined by the sash. Since sash are 6 feet long and are con- structed to slope lengthwise rather than crosswise, the width of the pit north and south should be a trifle less than 6 feet over all. The length is determined by the num- ber of sash desired. Since they are 3 feet wide, it should be some multiple of three. For example : A two-sash bed would be 6 x 6 feet, a three-sash bed 6x9 feet, etc. It is essential that the pit be well drained either naturally or artificially. If it is to be used in early spring, it is made the previous fall, filled with straw or manure and covered with boards to keep out rain and snow. When the bed is to be made this material is re- moved, leaving an unfrozen pit in which the new manure will heat more evenly and be more efficient. The upper or north side of a permanent hotbed is preferably 6 or 8 inches higher than the south side to give the proper slant to the sash. The north side may be about 15 inches and the south side about 9 inches above the surface of the soil. The sides are connected with crossbars placed SASIi-BED CONSTRUCTION 19 Fig. 4. — Plan for permanent hotbed even with the top, 3 feet apart, to serve as rests for the sash and to keep the frames from spreading. The sides and ends of the frame are well banked with fresh manure to conserve the heat. If the plants are to Fig. 5. — Permanent hotbed of concrete with cast-iron sills be grown in flats instead of directly in the soil, 2 inches of soil over the manure will be sufficient. If the plants are to be grown in the soil it should be 4 or 5 inches deep. 20 GREENHOUSES Temporary hotbeds are sometimes made by piling the manure on the surface of the ground and placing a shallow frame on top. Ground Leyei Fig. 6. — Plan for temporary hotbed. This form is wasteful of manure, and the settling of the pile is likely to warp the frame so that the sash will not fit tightly. It is most often used when a hotbed is needed and a pit has not been dug the previous fall. Another method is to dig a pit somewhat larger than the frame. This is filled with manure to a little above the ground level. m Fig. 7. — Type of hotbed used when a large amount of heat is required for a long time SASH-BED CONSTRUCTION 21 On top of this is placed a frame. The ad- vantage of this form of bed is that the frame settles with the manure, thus keeping the plants always the same distance from the glass. They are also warmer on account of the greater quantity of manure used. Manure for Heating. — Horse manure is al- most universally used in hotbeds, the pro- Fig. 8. — Usual type of concrete hotbed portion being about two parts solid excre- ment to one part straw or leaves. Manure which contains shavings is not satisfactory. Preparation is made lo or 12 days before the beds are wanted. The manure must be fresh- ly made and if not moist is dampened, prefer- ably with warm, though not hot water. More than enough manure to fill the pit is provided, for it will shrink somewhat in vol- 22 GREENHOUSES ume, and some will be needed to bank the sides and ends. It is placed in layers in a pile 4 or 5 feet wide, about 4 feet high and as long as necessary to contain the required amount, each layer being lightly tramped as placed. This is done under cover if possible. After two or three days, or as soon as the pile begins to steam, it is re-piled, the outside of the first pile being placed into the center of the second to encourage even heating throughout. The manure is moistened with warm water if it has become dry. If prop- erly made a vigorous fermentation will have set in after two or three days and it is then ready to be placed in the bed. If not thoroughly warmed through in three or four days after the second handling, it is re-piled again every few days until fermentation is established. Poor heating qualities may be the result of: (i) Manure from poorly-fed horses; (2) cold weather; (3) too wet or too dry manure; (4) too much litter in the man- ure and (s) shavings or swamp hay used as litter instead of straw or leaves. If a steady heat for several weeks is re- quired, the manure is placed in the pit in thin layers and trampled quite solidly, especially SASH-BED CONSTRUCTlOxN 23 along the sides and in the corners, keeping it as level as possible. Unless the hotbed is made so that the frame settles with tlip manure it must be filled to within 2 or 3 inches of the top of the south side of the frame to provide for settling. If it is proper- ly made, the temperature will soon rise to 120 degrees or more, but will gradually fall, and when it reaches 90 degrees the seeds may safely be sown. The temperature may be determined by plunging a reliable ther- mometer through the soil into the manure. When a hotbed is arranged to be heated by flues, drain or sewer tile is used, and the flues are connected with a fireplace at one end Fig. 9. — Hotbed arranged for heating by flues of the bed and a chimney at the other, so that the smoke and heat from the fire travel ,the whole length of the bed. Hot water or 24 GREENHOUSES steam pipes may be run through these flues if desired, or they may be placed along the sides of the frame above the soil. COLDFRAMES The forcing house, because of its conveni- ence, possibility of heat regulation and com- parative cheapness of operation is rapidly taking the place of the hotbed in a commer- cial way in the starting of early plants, but it is promoting the use of coldframes. These structures rarely receive artificial heat and Fig. 10. — A good type of coldframe with angle iron corners, A. are used largely for the purpose of growing and protecting plants during mid or late spring, after they have been started in the hotbed or forcing house and until they are ready to plant in the open. They are, in reality, simply hotbeds without artificial heat. When banked with manure and pro- tected with mats, these frames will protect tender plants at temperatures of 15 or 20 de- grees below freezing, if of short duration. SASH-BED CONSTRUCTION 25 The best frames are made of cypress and are joined at the corners by means of angle irons and bolts so that they may be easily taken apart for storage. Fig. 11. — Coldframe with sash removed. The sash rest on the crosspieces, X. When large numbers of frames are used in relatively mild weather, they may be very cheaply constructed by placing two planks parallel to each other and 6 feet apart. The plank on the north side is 12 inches wide and the one on the south side 6 inches wide. When the plants are removed the planks may be taken up and stored, or allowed to re- main, and crops may be planted between them. In mild climates, coldframes may be util- ized for starting early plants before danger from frost is over, although it is often 26 GREENHOUSES advisable to equip them with steam or hot water pipes, so that they may be heated in case of emergency. In the north, cold- frames are used for wintering violets, pansies and other semi-hardy plants; and farther south, for wintering cabbage, cauliflower and other plants which are started in the fall. ihelf for growing Fig 12. — A cold or storage-pit violets COLD OR STORAGE PITS In almost every florist's or vegetable grow- er's establishment there is need for an out- of-the-way frost-proof storage, to which light may be admitted on occasion. Such a stor- SASH-BED CONSTRUCTION 27 age may be easily constructed by excavating a pit similar to a hotbed pit, but deeper, so that the bottom will be well below the frost line. This must be well drained and lined with a brick or concrete wall, which should extend a few inches above the natural ground level to prevent water running in at the top, but is banked at the top with soil or manure. The pit may then be covered with sash and protected with mats and shutters described in a succeeding paragraph. In cold climates the pit is at least 5 feet deep. In very severe climates a mulch of manure 6 inches deep placed for a distance of 4 or 5 feet around the pit before the ground freezes, will effectually protect it. As the normal winter temperature of the soil be- low the frost line is considerably above freez- ing, coldpits furnish excellent storage for gladiola, dahlia and similar plants, and also for bulbs for winter forcing. A row of stor- age pits and coldframes along the south side of a greenhouse is of great convenience. The house must be provided with a gutter, or the frames set a foot or more away from the side of the house to guard against breakage 28 GREENHOUSES by snow or ice falling from the roof. A pit may be attached to the south side of a dwell- ing and connected with the basement. When the house is heated by a furnace this may be easily heated with little expense, and be used for growing vegetables or flowers through- out the winter. Fig. 13. — Sash-bed attached to basement of dwelling SASH-BED CONSTRUCTION 29 FORCING BOXES Forcing boxes or plant forcers are small coldframes with a single pane of glass, which are used to place over individual plants started early in the spring. They are used H LI Fig, 14. — Types of forcing boxes or plant forcers for protecting tomatoes, eggplants, melons and other heat-loving plants, and are re- moved as soon as continuous hot weather arrives. They are used also for forcing rhu- barb, asparagus and other vegetables in early spring, and for perennial flowering plants. Fig. 15. — Forcing buxcs in U6c on a commercial scale 30 GREENHOUSES GABLE ROOF SASH-BEDS Sometimes hotbeds and coldframes are made of two rows of sash set so as to form a gable roof. They have few advantages and many disadvantages when compared Fig. 16. — Gable roof sash-bed heated by manure with those of the ordinary type. A few years ago it was quite common to find sash- beds of this kind with a sunken walk under the ridge in which the workman could stand, the heat being supplied by decaying manure the same as in an ordinary hotbed. Such beds are convenient to operate in planting, watering and cultivating, especially in cold weather. They are not a profitable venture as a rule, as heat can be supplied more cheap- ly from coal than from manure. When an investment has been made in a house of this SASH-BED CONSTRUCTION 31 type it will be found to be economy to equip it with an inexpensive hot water system. MATS AND SHUTTERS Hotbeds and coldframes, when used in climates or seasons in which the temperature is likely to fall much below freezing, must be provided with supplementary covering's. Fig. 17. — Rye straw mats rolled for storage This is especially true when single-light sash are used. Rye Straw Mats, are extensively used for this purpose. They were formerly made by hand but are now made by machinery and are fairly reasonable in price. Each mat is 32 GREENHOUSES designed to cover two sash and should be 6x7 feet to allow for turning over the ends of the sash to keep out the wind. An ob- jection to straw mats is their weight, especi- ally when wet, and also the fact that mice are likely to work in them while they are stored during the summer. With careful handling they will last three or four years. Fig. 18. — Hot-bed covered with (C) double glass sash; (B) sash and straw mat; (A) sash, straw mat and shutter Burlap and Canvas Mats, which are pad- ded with waste cotton and quilted, are easier to handle than straw mats and are somewhat more durable. Though usually thinner than straw mats, they give practically as good protection. They have the added advantage of requiring less storage space, and are some- SASH-BED CONSTRUCTION 33 times treated with tar or other material of- fensive to mice. Waterproof Mats, made of heavy canvas, or sometimes of oiled or rubberized fabric, seem to have but little advantage over com- mon mats, except on coldpits, w^hen they are to be used during the entire winter. They are relatively expensive. Wooden Shutters, 3x6 feet in size, made of half-inch lumber, are occasionally used to place over the mats. Their chief value is in protecting hotbeds when made very early in the season, and for coldpits. Care of Sash-bed Materials. — As hot- beds, coldframes and the like, are used for on- ly a few months during the year, they are likely to be neglected and thus deteriorate rapidly. When many are used, their proper care may spell the difference between finan- cial success and failure. If movable frames are used, they should be taken down and stored as soon as the plants are out. If they are so constructed that they do not come apart, easily, they may be piled one above the other, cleaned and painted. 34 GREENHOUSES Sash should be cleaned and stacked under cover. Rain}^ days may be utilized in paint- ing them and re-glazing where necessary. It is economy to re-paint sash every season. Mats must be handled carefully and dried as soon as possible after they become wet by hanging them on a line or fence. They must be thoroughly dry when stored for the sum- mer and be kept where mice cannot get to them. CHAPTER III THE GREENHOUSE PROPER— GENERAL CONSIDERATIONS Location. — Having determined upon the geographical location, proximity to market and fuel supply and the investment in land which the business may be expected to war- rant, all of which are without the scope of this discussion, the points next to be con- sidered in the location of a greenhouse are as follows: (i) It should be such that the sun- light will not be obstructed at any time dur- ing the day. The probability of high build- ings being erected in the immediate vicinity should be taken into account. (2) It should be well drained either naturally or artificially and be absolutely free of danger from floods. (3) It should not be exposed to cold, bleak winds, as they will quickly make their pres- ence known in excessive fuel bills. A wind break of evergreen or other trees will be found very effective in protecting from winds but it will be several years before the trees will be large enough to be of much l)enefit. 35 36 GREENHOUSES (4) It should be comparatively level, or gent- ly sloping toward the south or southeast. Hillsides, if necessary, may be utilized by building houses of special design to be de- scribed later. (5) An unfailing supply of water at a reasonable cost should be assured. (6) If the houses are to be erected in connec- tion with other buildings, they should be on the south side if possible. For most plants the advantage of direct sunlight during the whole day cannot be over-estimated. (7) The possibility of enlarging the range by the addition of more houses should not be over- looked. Arrangement. — The arrangement will de- pend to some extent on the size of the range and the purpose for which it is to be used. If for private use only, convenience may often be sacrificed for appearance ; but for the commercial house the first thought in ar- rangement is for economy in operation. For a commercial house the following points in arrangement should be considered: (i) The direction in which the houses are to run. This will be fully discussed in Chapter IV. (2) The distance between the houses. This will depend on the size and height of the GENERAL CONSIDERATIONS 37 38 GREENHOUSES houses and on the value of the land. Little advantage, except in case of heavy snowfall, will be gained over the ridge-and-furrow sys- tem (see Chapter IV) by separating the in- dividual houses b}^ less than lo or 12 feet. A fair though not absolute rule is to space the J LJ— ^; — ^J^ — ' — P/amis Fig. 20. — Ground plan of range shown in Fig. 19 —Boiler room is in basement houses at a distance equal to two-thirds their height. (3) The workroom should be con- venient to all houses of the range, yet shade them as little as possible. (4) Other things being equal, the boiler room should be at the lowest part of the range in order to secure good circulation. When the houses are long it is usually best to have it near the center, and to insure circulation by deepening the GENERAL CONSIDERATTOXS 39 40 GREENHOUSES boiler pit, or in large establishments by the use of pumps or steam traps which will be discussed in the chapters on heating. Size of House. — There is no authentic data on the comparative efficiency of small and large houses. The large houses are relative- ly lighter, but there are other considerations. -X7f>- S^f^vKE Building AND BOILCR FtooM JO 12 15 14- 15 16 17 18 19 20 11 -I7f)- Fig. 22. — Ground plan of range shown in Fig. 21 As a rule the eastern growers favor separate large, high and wide houses while those of the Middle West prefer lower and narrower connected houses. The present tendency is to build larger houses than formerly. Of i6o florists and vegetable growers whom the author has consulted, 148 or 88 per cent, ex- pressed themselves in favor of houses rang- ing from 24 to 40 feet in width. These are undoubtedly the most popular widths at the present time, the length varying from 100 I GENERAL CONSIDERATIONS 41 4.2 GREENHOUSES to 500 feet or more. A discussion of the ad- vantages of high, wide, single houses and of low, narrow, connected houses is given in Chapter IV. Pitch of Roof. — The pitch of a roof means the degree of slant or the angle of divergence from the horizontal. The glass of the roof not only allows the light, heat and chemical Fig. 24. — The pitch of the roof is measured at A rays to pass through it, but it also acts to some extent as a mirror, thus reflecting a part of the rays. The amount lost by re- flection is proportional to the angle of in- cidence. Thus, if the sun's rays fall upon the roof at right angles, little or none is lost by reflection; but when they fall at a less GENERAL CONSIDERATIONS 43 o c3 CO 13 ?co O 4> . o C S o U be 44 GREENHOUSES Fig. 26. — Diagram showing how heat and light are lost by reflection angle, the amount reflected increases as the angle of incidence increases. The amount of the sun's energy lost by reflection when the rays strike the roof at various angles is shown in the following table. Table showing per cent, of sun's energy lost when the rays strike the glass at different angles Angle of ray Loss by reflection 60 degrees 2.7 per cent. 50 " 40 " 30 " 20 " 15 " 10 " ". 3.4 5.7 11.2 22.2 30.0 41.2 It is apparent that the maximum amount of the sun's energy may be secured by a roof presenting to its rays an angle of 90 degrees. It is especially important that the energy GENERAL CONSIDERATIONS 45 of the sun be conserved during the short days of winter. At its lowest period the sun rises, in the latitude of New York, scarcely more than 25 degrees above the horizon at noon. In order for the roof to present an angle of 90 degrees to the sun's rays at this season, it would need to have a pitch of 65 degrees. Fig. 26a. — Diagram showing pitch of roof necessary to present an angle of 90 degrees to the sun's rays in winter Such a roof would be (i) very expensive to build and maintain, (2) would present too large an amount of radiating surface for the space covered and (3) would be too high to be practical in houses more than 10 or 15 feet wide. If, however, we reduce the pitch to 35 de- grees, the sun's rays will strike the roof at an angle of about 55 degrees which, by refer- ence to the table, will be seen to incur a loss 46 GREENHOUSES by reflection of between 2 and 3 per cent, on- ly. Roofs of this pitch are not difficult to build, and do not present so large a radi- ating surface for the area covered as do roofs having a pitch of 65 degrees. Roofs having a pitch of less than 26 degrees are seldom satisfactory because the snow does not clear from them well and they are likely to leak. The water of condensation which forms on the inside of the roof is also likely to drip up- on the plants when the pitch is less than about 26 degrees. When the pitch is greater, the water will usually follow down the glass to the edge of the house. In even-span houses (see Chapter IV) the pitch of the roof varies from 26 to 35 degrees, 26 and 32 being the most popular. In some specially constructed houses it is as great as 45 degrees. Most builders equip houses up to 25 feet in width with roofs having a pitch of 32 degrees, and above 25 feet with roofs having a pitch of 26 degrees. Measuring the Pitch. — The degree of pitch of any even-span roof may be determined tri- gonometrically when the width of the house and the height of the ridge is known or can be measured. If the house illustrated in GENERAL CONSIDERATIONS 47 Fig. 24 is 20 feet wide and the ridge is 7 feet above the eaves, the value of the angle, known as A, may be found by the following formula: Tang. A=^ equals Tang. A— - equals Tang. A=,yoo or A=35 degrees. Should the house be of uneven span it is only necessary to measure the distance corresponding to a (Fig. 24) and apply the same formula. When this is not con- venient, a plumb bob may be dropped from any part of the roof, as at c, and the distance measured from the roof to the point c^, where it cuts a horizontal line or straight edge from the point where the roof joins the wall. This distance may be substituted for b in the formula, and the distance from c^ to the in- tersection of the roof and wall may be sub- stituted for a. To avoid error the triangle thus formed should be as large as possible and care taken to see that the lines are per- fectly vertical or horizontal, as the case may be. By referring to the following table the angles in degrees and minutes formed by roofs on houses of various widths and heights of ridge may be quickly found. The figures in the left-hand column correspond to half the width of even-span houses or to the dis- tance represented by a in the above formula. 48 GREENHOUSES Table showing angle formed by roofs on houses of different widths and heights of ridge One half Heigh t of rid ge in feet wi( 1th 4 5 6 7 8 9 10 inf eet o ' O ' O ' O ' O ' O ' O ' 6 32 21 39 48 45 49 24 . . . • • • . • 7 29 44 35 32 40 36 45 48 49 • • • • 8 26 33 32 36 52 41 11 45 48 32 9 23 57 29 3 33 5 37 52 4138 45 10 26 33 30 58 35 38 39 4159 11 24 26 28 36 32 28 36 2 39 17 4213 12 22 57 26 33 3015 33 41 36 52 39 41 13 . . . . 24 47 2818 3136 34 42 37 34 14 . . . . . . . . 23 12 26 34 2944 32 44 35 34 15 . . . . . . . . . . . . 25 28 4 3100 33 40 16 .. .... .... 24 13 26 32 It is perhaps more often desired to find the length of rafter necessary to form a roof of given pitch on a house of given width, than to determine the pitch of a house already erected. This may also be solved trigono- metrically. For example: Suppose it is de- sired to know the length of rafter necessary to form a roof with a pitch of 35 degrees on a house 20 feet wide. If the roof is to be of even span, as shown in Fig. 24, we will have a right angle triangle, A B D, the base of which is known to be half the width of the house, or 10 feet. If the angle A is to be 35 degrees then: Cosine A=^^ equals .81915= i?. Transposing, X=-^^or X=i2.2 feet. GENERAL CONSIDERATIONS 40 This formula is also applicable to an un- even span roof provided the distance from the point directly underneath the ridge to either side of the house is known. For example : In a 20-foot three-quarter span house, the base corresponding to a of the triangle A B D in Fig. 24 is either two-thirds or one-third of 20 feet, according to which side of the roof we wish to measure. In the following table will be found the lengths of rafters required to form roofs of various angles on houses of different widths. The figures in the left-hand column corre- spond to half the width of an even-span house or the horizontal distance from the eaves to a point directly underneath, where it is de- sired to place the ridge. Table giving length of rafters necessary to form roofs of various angles on houses of different widths One ha If Pitch in de grees width 26F 30° 32° 34° 35° 40° 45° of house in feet LENGTH OF RAFTERS IN FEET 6 6.67 6.92 7.07 7.23 7.32 7.80 8.48 8 8.90 9.23 9.44 9.65 9.76 10.70 11.31 10 11.12 11.54 11.79 12.06 12.20 13.05 14.14 12 13.35 13.84 14.14 14.46 14.64 15.60 16.96 m 13.90 14.43 17.73 15.09 15.25 16.33 17.67 15 16.80 17.32 17.68 18.09 18.30 19.57 21.21 20 22.44 23.08 23.58 24.12 24.40 26.10 28.28 25 27.80 28.86 35.46 30.18 30.50 32.66 35.34 CHAPTER IV GREENHOUSE ARCHITECTURE Architecturally, the different forms of greenhouses are named and recognized main- ly by the style of roof. Lean-to or Shed-roof Houses. — These are the simplest forms of greenhouses; likewise the least expensive and least satisfactory. There is little excuse for building separate houses of this type, but they may be made to serve a useful purpose when erected against the side of a building or against a steep side hill. They usually extend east and west, with the high wall to the north and the roof sloping toward the south. For commercial purposes they are of little value, as they ad- mit light from only one side, and but little direct sunlight, except for a few hours in the middle of the day. They may be utilized for growing ferns and other plants requiring little direct sunlight, also for starting early plants, or as grape or peach houses, the vines or trees being trained against the north wall. 50 GREENHOUSE ARCHITECTURE 51 Lean-to houses not only have the advant- age over other types in less first cost, but also in cost of maintenance. They have less glass surface in proportion to the area cov- ered; hence there is less breakage, and for the same reason they radiate less heat. For amateur use, especially when they can be erected against the south side of the dwell- ing, they may be built and operated at small cost and will afford much pleasure. Even-span or Span-roof Houses. — In these houses, as the name indicates, the sides of the roof are of equal length. They are the most popular form, fully 80 per cent, of all houses of recent construction being of this type. They are superior to the lean-to in that they admit light from two sides, and also because they may be run either north and south, or east and west, as may be de- sired. On this point, however, practical growers disagree, some preferring the east and west arrangement, others the north and south. Theoretically, the points in favor of and against each seem to about counterbal- ance. They are stated in the following paragraph. The north and south arrangement permits 52 GREENHOUSES direct sunlight to fall on both sides of the house for an approximately equal time dur- ing the day, thus giving all the plants in the house an equal chance. It also permits the workroom to be placed on the north end, where it will not shade the house. The principal disadvantage is that during the middle of the da}^ when the sun's rays are most potent, they strike obliquely against the roof and much heat and light is lost by reflection. Moreover, a large part is cut off by the sash bars and rafters. In the east and west arrangement, the di- rect sunlight enters from the south side only, and in the morning and afternoon strikes the roof obliquely. During the middle of the day, when it is most effective, it strikes al- most at right angles, although it is not even- ly distributed and the plants on the north side of the house receive much less than those on the south side. This would seem to be a serious fault, but in practice is less serious than in theorv. Of no o-rowers whom the author consulted on this point, 38 were in favor of the north and south ar- rangement, 42 were in favor of the east and west and 30 expressed the opinion that there is little or no difference. GREENHOUSE ARCHITECTURE 53 54 GREENHOUSES Uneven Span Houses. — The uneven dis- tribution of light in even-span houses running east and west early led to the experiment of cutting off the north one- fourth, so as to make an uneven or three- quarter span house. The following advant- ages are claimed for these houses: (i) They secure a more even distribution of direct sun- light to all plants. (2) The north span ad- mits indirect light which insures better re- sults than may be secured from a lean-to house. (3) The heat is more evenly distri- buted than in a lean-to house. They are often used in growing roses and other plants requiring a maximum of light. The con- struction of uneven span houses has been varied from time to time, the general ten- dency being to lower the north wall to ap- proximately the height of the south wall. This arrangement insures even better distri- bution of light and does away with the neces- sity of elevated benches. Uneven span houses are sometimes used for growing lettuce and other vegetables di- rectly on the ground instead of in benches, especially on sloping locations. Modern greenhouses are so much lighter than the older types that the advantages of the un- GREENHOUSE ARCHITECTURE 55 56 GREENHOUSES even span house in this connection are hard- ly worth considering. They are much less commonly built than formerly. Uneven span houses are sometimes constructed with the short span to the south with a pitch of 40 degrees or more. This brings the roof more nearly at right angles to the sun's rays, but has little or nothing to recommend it. Ridge-and-Furrow Houses. — A ridge-and furrow house is in reality simply two or more houses joined together. They may be even span or uneven span so long as the side walls are of equal height. The advantages of this form of construction may be mentioned as follows: (i) They are less expensive to build than separate houses of similar size, on ac- count of the saving in side walls. (2) Not only is there a saving in the number of side walls, but the interior walls may be of cheap construction or may be left out entirely, the weight of the roof being supported by posts alone. (3) Considerable saving is made in la- bor because easy passage may be had between houses. (4) They conserve ground space which is often a considerable item. (5) The houses in the center are protected from wind by those on either side and the radiation is GREENHOUSE ARCHITECTURE O I thus reduced. (6) Because there is less ex- posed wall surface, and because the interior houses are protected, they require less fuel than do separate houses. One of the chief objections to the ridge- and-furrow system of construction is the dif- Fig. 29. — Ridge-and-furrow houses wrecked by a storm ficulty of removing snow from between the houses in regions subject to heavy snowfall. Other disadvantages are: (i) The center houses are shaded more or less, (2) side light and side ventilation can not be had, and (3) soil and other materials must be carried into the house from the end instead of being put in at side openings. The latter is a serious ob- 58 GREENHOUSES jection only when the houses are long and narrow. The above remarks refer only to separate and connected houses of similar sizes. At the present time there is a difference of opin- ion as to the advantages of the single wide and high house over the small and lower Fig. 30. — Diagram showing that the same amount of roof is required for several small, connected houses as for one large house covering the same area if the pitch is the same. a+b+cH-d+e-f-f=A+B. houses connected in the ridge-and-furrow system. Contrary to the prevailing notion, the same amount of glass is required by each system if the roofs are of the same slant or pitch, The following advantages are claimed for the large, single houses: (i) They are more easily kept at an even temperature, (2) venti- lation may be secured without subjecting the GREENHOUSE ARCHITECTURE 59 plants to cold drafts, (3) they are lighter, (4) they are more easily cared for, (5) the light is more equally distributed over the whole house, (6) they quickly clear themselves of snow, (7) they contain a larger volume of air, and (8) they require fewer ventilators and less ventilating machinery. On the other hand the following disadvant- ages are pointed out: (i) Their great height makes them a target for storms which in winter cause a greater radiation of heat, (2) they are less easily re-painted and re-glazed, and (3) the first cost is greater. Notwithstanding these objections, how- ever, the single house of moderate size (40 to 60 feet in width) seems destined to become more and more popular. Curved-roof Houses. — Curved or curvilin- ear roofs are now seldom seen, except on conservatories and show houses. Their chief use is for ornamental effect. They originated in an attempt to so arrange the glass as to more perfectly intercept the direct rays of the sun, but in practice they have proved lit- tle, if any, superior to the straight roof, and the expense is considerably greater. They have never come into general use in a com- 60 GREENHOUSES mercial way. Curved-roof houses are made to use either curved or straight glass. Side-hill Houses. — Mention has already heen made of one of the forms of this type of house. Sometimes a modification of the ^7/////' Fig. 31. — Diagram of a side-hill range ridge-and-furrow house is utilized for side hill construction. Side-hill houses are not recommended when well drained, level land may he secured, because of the disadvantage of working at different levels. Curved-eave Houses. — The shade caused by eave plates and gutters, the difficulty of keeping them in repair and their interference GREENHOUSE ARCHITECTURE 61 62 GREENHOUSES with the clearing from the roof of ice and snow in winter, has led to the adoption by several firms, of the curved-eave construc- tion. For small and medium-sized houses the increase in light is very noticeable. In larger houses it is not so apparent. The ex- pense for glass is somewhat greater on ac- count of the curved panes required. Circular Houses. — These belong in a class with the round barn and octagonal house — excellent in theory but impractical in use. Their first cost and the expense in mainten- ance places them without the range of econ- omy as commercial houses. As ornamental houses in parks and private places, and for the growing of tall tropical plants they have their place. CHAPTER V STRUCTURAL MATERIAL Practically all the material, whether it be wood or metal, which goes into the construc- tion of a modern greenhouse, is milled or shaped at the factory. It will almost never pay the prospective builder to attempt to use material made by any but specialists in this line of work. There are several such firms in this country. Greenhouse construc- tion, then, so far as the individual builder is concerned, becomes simply a matter of choos- ing the kind of material he desires to use; ordering it from a responsible manufacturer and assembling it or placing it in its proper position. Most greenhouse construction firms have certain standard or stock houses which they ship complete, even including nails, paint and putty if wanted, at a definite stated price; and they will erect them if it is desired. They will also design and l)uild a house or range of houses to suit any given condition. 64 GREENHOUSES O O - 03 »-. en c/) -4-1 e G ^- N (U 4-. ot;; ^^ tfl S «) ^ rt •« o ^1 „ to -^ X XI C ^ t« o c c ^ ^ u c I. - -^ ^'-^ CO oj r: b£) ./-///^i^[ Glazing Bars. — These are bars which are spaced along the sides and ends of the house to which the glass is fastened. They are much the same as sash bars, which will be described later, except that they are usually somewhat smaller and are not provided with l^^f^- grooves to the drip. conduct ^ , Fig. 38. — Cross section of Corner bars corner bar STRUCTURAL MATERIAL 69 serve the same purpose as glazing bars, ex- cept that they are so milled that they will take the glass from both the sides and the ends of the house. One is used at each corner. Side Posts. — These posts bear the weight and side strain of the roof. They may be of wood, gaspipe, or structural iron or steel. Their size will depend on the height of the wall and the width and construction of the house. Wood posts 4x4 inches, 2 or 2^- inch gaspipe, or /^ x 3-inch structural iron or steel are usually considered amply strong for most houses. The gaspipe and steel posts are usually set in concrete and mason- ry. It is best to set the wood posts in the same manner. Occasionally the structural steel, posts are bolted to iron sills which cap a concrete or masonry wall. Sash Bars. — The sash bars are among the most important of all the members which go to make up a greenhouse. They must be strong enough to carry the weight of the glass, yet be of such form and size as to cast the least possible shade. They are of various forms and sizes. Bars made en- tirelv of metal are seldom satisfactory for 70 GREENHOUSES the following reasons: (i) They are likely to expand and contract considerably with changes in temperature, thus loosening and A. t ■ £. r. Q. H. Fig. 39. — Types of wood sash-bars. E, F, and H are used for butted glazing; G is used for double glazing often breaking the glass. (2) The extreme cold to which they are subjected on the out- side, as compared with the warm tempera- ture on the inside of the house, has a ten- dency to cause them to warp and thus break the glass or cause it to fit poorly. (3) As all metals are ready conductors of heat, much is lost by radiation when they are used. (4) In STRUCTURAL MATERIAL 71 cold weather they become so cold as to cause the moisture in the air inside the house to condense rapidly on them, which results in a large amount of drip. V^arious types of bars have been invented in an attempt to over- come these difficulties. Fig. 40. — Two types of patented metal sash-bars Wood sash bars are not good conductors of heat and condense but little moisture, but moisture from the glass finds its way to the sash bars, so that they are usually made with a groove or furrow on each side, w^hich conducts the moisture down to the eaves. The most common size of wood sash bars is i'>^ X 2>^ inches. Larger bars are used for special purposes. 72 GREENHOUSES (I ■ Fig. 41. — King "channel bars" Fig. 42. — "U-Bar" type of sash-bar STRUCTURAL MATERIAL 73 J Gable Bars or Gable Rafters. — (jable rafters are used at the ends of the roof and are made so as to re- ceive both the glass of the roof and that of the end of the house. They should be large and strong- enough to give ri- Fig. 43.-Gable rafter gidity to the gable. Drip Gutter. — The purpose of the drip gutter is to carry away the water formed b y condensa- tion inside the house, whicli is conveyed to it by the sash bars. The pipes leading from it should empty into a cistern or sewer con- nection inside ,i 1 , I'ig. 44. — Combination eave plate the house, or be .^^ gutter 74 GREENHOUSES carried out below the frost line. This is neces- sary to prevent freezing, as the greatest drip is in the coldest weather. In some forms of construction where pipe side posts are used, they are utilized as conductors of the drip water, but the saving thus accomplished is usually more than counter-balanced by the early rusting out of the posts. Gutters are made of wood, zinc, tin and galvanized iron. Purlins. — Since sash bars must be small to minimize the amount of shade, it is evident that on wide houses they cannot carry the weight of the glass without support. This is accomplished by means of purlins. They run lengthwise of the house, and are them- selves supported by purlin posts, by purlin braces, by rafters or by some form of truss work to be described later. When ordinary wood sash bars are used with glass i6 inches wide, the maximum dis- tance for safety between purlins is not more than 7 feet. For example: If the sash bars are more than 7 feet long, one purlin should be used. If they are more than 14 feet long, two purlins should be used, and so on. This distance decreases as the size of the glass in- creases since there are fewer bars to sustain the same weight. STRUCTURAL MATERIAL 75 Purlins may be of wood, gaspipe or angle iron. Wood purlins, because of their size (1^x3 inches), cast so much shade that they are now little used. Purlins of i>4-inch gas- pipe are very satisfactory. They are fast- ened to each sash bar, and are supported by posts or braces every 8 feet along their Fig. 45. — Pipe-strap for fastening sash-bars to purlins length. A very satisfactory means of fast- ening them to the sash bars is by means of a U-shaped pipe-strap. This is placed under the purlin and fastened to the sash bars by means of screws. Ridge. — The ridge furnishes a means of fastening the upper ends of the sash bars and also serves as a support for the ventilators. 76 GREENHOUSES It is milled from a 2 x 4, or a 2 x 6-inch tim- ber, the size depending on the width of the house. The form varies according to the method of attaching the ventilators. (See Chapter VIII). Ventilators. — These are fully discussed in Chapter VIII. Ventilator Header. — This is a member up- on, which the lower side of the ventilator rests.- It is cut and grooved at the factory so as to fit over the sash bars and to receive the edge of the glass of the roof in its lower side. Sash Hanging Rail. — When side ventilat- ing sash are used a special piece is sometimes placed immediately under the eave plate or gutter, to which the sash are hinged. This is known as a sash hanging rail. Sometimes the sash are hinged directly to the plate or gutter. Weather Strip. — Because of their construc- tion and the method of hanging, the roof ventilating sash do not fit down tightly upon the sash bars but leave wedge-shaped open- ings. These are closed by pieces known as weather strips. STRUCTURAL MATERIAL 77 Rafters. — Their use is now confined al- most wholly to all-metal frame houses which are discussed in Chapter VI. KINDS OF WOOD Three kinds of wood are now being used in greenhouse construction : Cypress, cedar and California redwood. Of these the first two are preferred on account of the higher '^^^H^^H^^Hk Fig. 46. — "Pecky" cypress cost of redwood. There is little difference in the durability of cypress and cedar. If well framed, and if thoroughly painted when erected and at least once in two years there- after, either will last a lifetime. Pecky cypress is the heartwood from old trees. It is full of holes or "pecks" and is often too "shaky'' for sash bars and other small members, but it is one of the most dur- able woods known. It is used chiefly for benches, and in other places where ordinary lum])er decays rapidly and where great strens^th is not needed. 78 GREENHOUSES FRAMING ' The woodwork of a greenhouse always be- gins to decay at the joints. For this reason particular attention is paid to the framing. All joints are made to fit closely, and before putting together each piece should be primed with a thin coat of lead paint. The joints Fig. 47. — The concentric system of construction are then given a heavy coating of thick white lead and put together while the paint is still green. In buying greenhouse material it is al- ways well to buy all the woodwork from one firm and to give the concern a careful de- scription of the house, together with a draw- ing showing the width, height and length of the house, the pitch of the roof, size of glass to be used, etc. The firm will then send the STRUCTURAL MATERIAL 79 woodwork (if it is so directed) cut so that it may be fitted together with but Httle trouble. It should be specified, however, that it be well seasoned and not warped. Warped millwork, especially sash bars and glazing bars, are exceedingly difiicult to put in proper position. Some factories now build their eave plates and sash bars on the concentric principle, which does away with the necessity of cut- ting the ends of sash bars differently for roofs of diiTerent angles. CHAPTER VI FRAMEWORK— METHODS OF ERECTING The two cardinal virtues of a good green- house framework are these : It must be strong and Hght, and it must cast but little shade. The greatest advance in greenhouse con- struction in the last quarter of a century has been in the framework. The old houses with their high, solid walls and heavy woodwork are dingy and dark, when compared with the modern house, 90 per cent, of which is glass, with little or no solid wall above ground. The framework of these houses casts but a frac- tion of the shadow produced by the old-style frame, yet it is so perfectly rigid against storms and snow that the large panes of glass are seldom broken or even loosened in their setting. Three general classes of framework are used: (i) Wood frame, in which all members, including the posts, are of wood; (2) semi- iron frame, in which the posts, purlins and purlin posts are of pipe or structural iron, 80 FRAMEWORK 81 bi) U < , o E U o ■^ r-i o O u T 7 f— u ~ -!-• ^ (/) ( ; r- o u U -i-> <-t-l u t£ C 'M '■/ —rf t: ^ •. (/) rt u -^-* l_l a; O 1 U »-— 1 ., y n 00 82 GREENHOUSES and (3) all-iron or all-steel frame. In wood and semi-iron construction, rafters are sel- dom used, the sash bars performing this func- tion as well as their own. These forms have the advantage of being somewhat cheaper than the all-metal frame construction, and have the additional advantage that the ma- terial may be cut and fitted on the job by any experienced workman. Wood frame houses cast more shade than semi-iron, and are less durable, especially the posts. Semi-iron houses are very durable, and for houses of medium width, are very satisfactory. Probably more houses of this type have been built during the past ten years than of all others, though the all-metal frame house is now gaining in favor. This is especially true in the East, where large houses are coming into vogue. The all-metal frames are cut and fitted at the factory and are then shipped, knocked down, to the place of erection. Most styles of all-metal frames have rafters, which are bolted to the side posts by means of gusset plates to form bents. The bents are then placed in position and secured there by stays and purlins. Upon this framework are then bolted the wood sash bars and glazing FRAMEWORK 83 bars. Metal sash bars, as before mentioned, seldom prove satisfactory. The framework of such houses is practically indestructible, and when the woodwork decays it can be re- placed upon the old framework. Usually the weakest part of a greenhouse is the gable. It should be well framed and securely tied to the purlins and other parts of the framework. METHODS OF ERECTION Foundations and Walls. — In the old-style high, solid wall greenhouse, the wall was a source of much perplexity, especially the high north wall of the uneven span house. In modern houses, however, the solid wall is seldom higher than the top of the benches, when benches are used, or only a few inches above the surface when plants are grown on the ground. The remaining part of the side- wall is constructed of posts and glass, thus giving more light. The chief difficulty with the high, solid wall was that the extremes of temperature between the outside and inside in cold weather caused them to disintegrate rapidl}'. This was particularly true with masonrv walls. 8^ GREENHOUSES Modern greenhouse walls, for commercial houses, are almost always of concrete and, being low, give little trouble. Concrete blocks and hollow building tile are much used. The chief requisite is that the founda- tion shall reach below the frost line. The common practice is to dig a trench 12 or 15 inches wide and 3 feet deep and fill with coarse concrete to within a few inches of the surface. A form is then built of lumber .to the height required and filled with concrete. When the concrete has "set," the form is taken away and the sides of the wall plast- ered with a cement mortar. In wet, springy soil it is often desirable to lay a row of drain tile along the outside of the wall arid nearly to the bottom of the trench, to carry ofT the water. Concrete walls are usually much more satisfactory than either brick or stone. They should be from 8 to 12 mches thick, according to their height and the side strain to which they are subjected. Usually 8 inches is suf- ficient. In wet soils when the boiler is placed below the surface, it may be necessary to waterproof the walls. For data on concrete construction see Chapter XV. FRAMEWORK 85 Wood Frame Houses. — These are quite satisfactory when a cheap house is wanted for a comparatively few years. The side posts, which may be of cedar or cypress, and 3x4 inches in size, are placed 8 feet apart in holes 3 feet deep, and extend to the height Fig. 49. — Plan for an all-twood frame greenhouse decided upon for the side walls. They are then placed in alignment and the holes poured full of thin concrete which soon hard- ens. The end posts are similarly placed, ex- cept that they extend only to the height of the boarded-up portion of the wall. S6 GREENHOUSES ^ The next step is to place the center posts, which are usually 2 x 3 or 2 x 4 inches in size. The height of the ridge having been determined (see Chapter III) these posts are cut long enough to allow the lower end to be set in the ground about 2 feet. They are then put in alignment and embedded in concrete the same as the side posts. The ridge is then put in place on top of these center posts, and the eave plate on top of the side posts, all joints being set in thick white lead paint. The sash bars on a house over 12 feet in width must be supported with purlins, but it is not necessary to support them with two extra rows of posts. A perfectly safe and much more convenient way is to support them with arms or braces from the center posts. This saves valuable ground space, and the arms serve to stiffen the center posts as well. The length and position of these arms may be determined by placing a straight edge from ridge to eave plate in just the position the sash bars will occupy, and nailing the arms fast, first allowing for the thick- ness of the purlin. A good mechanic would have determined this before the posts were FRAMEWORK 87 set, and have nailed the arms in place before raising them. The amateur, however, will find it best to put them in place after the posts are up, or at least to put up a trial post and then make the others after it as a pattern. The next step is to nail on the purlin, and then it is ready for the sash bars, which are spaced carefully so that the distance from rabbet to rabbet is about one-eight-inch greater than the width of the glass. This can best be accomplished by using a board about one-eight-inch wider than the glass, and nailing the bars so that the rabbets fit snugly against it along their whole length. The board can then be removed and used to space the next, and so on. The side and end posts are next boarded up to the required height, using two layers of matched lumber with paper between. The bottom board, at least, must be of best qual- ity pecky cypress to guard against decay. Glazing bars may now be fitted along the sides between the eave plate and the glazing sill, and between the glazing sill and the gable rafters. Corner bars are placed at each corner. 88 GREENHOUSES It will also be necessary to make a frame for the door at one end, and to reinforce the gable glazing bars with 2 x 4-inch scantling. The house is then ready for glazing, instruc- tions for which will be found in Chapter VII. If cypress or cedar lumber is used through- out, and if kept carefully painted, a house like the above should last for fifteen or twenty years. The most vulnerable parts are the posts, especially the portion where they enter the cement. They should be painted regularly once each year at this point. While these houses do not admit as much light as either a semi-iron or an all-iron frame they will give excellent service. A poorly built all-wood frame house is a constant expense for maintenance. Semi-iron Frame Houses. — Two methods of framing a semi-iron frame house are shown in Fig. 33. The method shown on the left requires twice as many purlin posts as the one on the right. In each case gaspipe is used. The work of erecting differs but little from that described for wood frame houses, except that pipe working tools are required, and a little more skill is necessary. An endless variety of fittings may be had FRAMEWORK 89 for this style of framing, which makes the joining of the frame work comparatively easy. If it can be procured, genuine wrought- iron pipe is best used instead of the steel pipe now commonly sold. Steel pipe rusts out Fig. 50. — Two methods of framing a semi-iron house For others, see Fig. 33 much more quickly. In this style of house the wall is usually of concrete and may be only a few inches above the surface of the ground, or any height desired. The side posts which are usually of 2-inch pipe are put in position and stayed before the concrete is poured in, so that when the wall has set they are per- fectly rigid. Adjustable brackets which fit on the top of the posts, and to which the eave plate or gutter is attached, make pos- sible the correction of trifling variations in height. Bolts are set, heads down, in the top of the wall while it is soft, and project upward 2 or 3 inches. These are used for fastening down 90 GREENHOUSES the sill, which is bored to fit over the posts and bolts and is secured with nuts. No posts are set in the end walls, but the bolts are set the same as in the side walls and are used for the same purpose. In some cases the posts are set in the ground and the side walls are constructed of two layers of matched lumber. The purlin posts and other supports are put in position much the same as in the wood frame house, except that in- stead of being embedded in concrete, they are sometimes provided with foot pieces and rest on small concrete piers. Split malleable iron castings may be had in almost every conceivable form for joining the frame together. These arc fastened by bolts and set screws, so that it is not necessary to thread the pipe. The sash bars are fastened to the pipe purlins by means of U-shaped clips or pipe-straps, which are secured to the bars by means of screws. Purlins are usually made of one and Fig. 51. — Struc- tural steel post with board wall FRAMEWORK 91 a quarter-inch pipe and should be supported by posts every 8 feet. Purhn posts are usual- ly of one and a half-inch pipe and braces of one and a quarter-inch pipe. A well-built house of this type, if well cared for, should last a lifetime. Fig. 52. — Section of truss-frame greenhouse. The frame is made of gaspipe Semi-iron frames are also made from struc- tural iron instead of pipe. They are just as satisfactory, but are not so easily worked, and are usually cut and fitted at the factory. All-metal Frame Houses. — There are three types of all-metal framework: (i) Those in which the roof is supported by interior posts, much the same as in the wood or semi-iron houses. (2) Those in which the roof is sup- 92 GREENHOUSES ported by a truss work, thus doing away with all interior posts (sometimes known as truss- frame). (3) A combination of the above forms (known as a combination truss-frame) is used in houses so wide as to make the truss-frame impractical. This is commonly used in houses over 40 feet in width. Fig. 53. — Section of combination truss-frame green- house, 172 feet wide As has already been mentioned, all-metal frame houses usually have wood sash bars and glazing bars, but they are not considered as parts of the framework. In these houses the completed framework is entirely of metal, the wooden members being fastened to the frame with bolts or screws and serving only to hold the glass in place. In many all-metal frame houses, especially when the roof is supported by inside posts, it is common to bolt an iron or steel sill to the wall and then bolt the side posts to this sill. A method of erecting a modern combina- tion-truss frame house, 73 feet wide and FRAMEWORK 93 94 GREENHOUSES nearly 30 feet high, to the ridge, is shown in Fig. 54. This work was done entirely by the owners and their ordinary help, without any expert superintendence and at a material saving in cost. The method was comparatively simple. The material was first carefully distributed on the site selected, and a trench dug for the foundation. The gable trusses were then bolted together, while another gang of men began setting and guying the side posts. The trench was then filled with concrete, making the side posts rigid. Next the in- terior posts were put in place. The first step in putting up the rafters was to fasten the lower ends to the tops of the side posts loosely, so that they would move easily, and then raise the other end into place by means of a pair of "shears,'' made of two pieces of 2 x 4-inch scantling. When these had been securely bolted in place, the gable truss, which had been previously assembled, was swung into place by means of a block and tackle, working from a boom. All that remained was to insert and tighten the bolts, put the purlins in place and move on to the next bent. The author was told by the owners of this house that it was erected FRAMEWORK 95 96 GREENHOUSES with greater ease than any semi-iron house they had ever built. , Fig. 56. — A method of erecting small all-metal frame houses Structural steel is most largely used in truss-frame houses though gaspipe is now quite popular. It is claimed for gaspipe that it costs less than structural steel and that it casts less shade. Some objection has been urged against houses constructed of gaspipe on account of a lack of rigidity, but as now constructed they give very satisfactory serv- ice. Houses of this type are regularly sup- plied by manufacturers up to 54 feet in width, without center supporting posts. It is prob- ably safest to have two rows of supporting posts in houses more than 40 feet in width. CHAPTER VII GLAZING AND PAINTING Greenhouse glazing is an art in itself. Most construction firms employ professional glazers. It is, however, an art that may be readily acquired. Many owners do their own glazing when occasion requires, or have it done by their ordinary help. The method of glazing greenhouse roofs is not the same as that used in glazing window sash. When glazers from glazers' shops or hardware stores are employed, precaution should be taken to see that they understand the differ- ence. Glass. — The glass commonly used in greenhouse glazing is clear, white, sheet or window-glass of either A or B grade. Glass with a pronounced green or bluish cast is to be avoided, as it obstructs a large part of the heat, light and chemical energy of the sun's rays. Clear, white window-glass ordinarily ab- sorbs about 30 per cent, of these rays ; green, 97 98 GREENHOUSES from 40 to 50 per cent.; and blue, from 50 to 80 per cent. Glass known as A, or first grade, is blown from the top of the retort and is of bet- ter quality than the B, or second grade, which may contain some foreign matter or settlings. Some of the less regular panes from the first blowing and those containing small air bubbles are also placed in the B grade. When it is essential that the great- est possible amount of light be had and tight glazing is necessary, A grade is used. In most commercial constructions B grade will give satisfactory results. Poorer grades are not satisfactory for greenhouse work. The cost of B grade is about 85 per cent, of the price of A grade. Both A and B grades may be had in two weights or thicknesses, known as single-thick and double-thick. Single-thick runs about 12 panes to the inch and weighs from 19 to 21 ounces per square foot. Double-thick runs about 8 panes to the inch and weighs from 26 to 29 ounces per square foot. Double-thick is almost always used when the panes are more than 8 X 10 inches in size. It obstructs but little more light and is much more durable, especially against hail. GLAZING AND PAINTING 99 The price of single-thick is from 60 to 70 per cent, of the cost of double-thick. Amer- ican window-glass is the best that can be procured. The price varies greatly from year to year, probably more than does the price of any other standard building material. American-made glass is packed in boxes of about 50 square feet each. Foreign glass comes in boxes of approximately 100 square feet each. The number of lights per box of the various sizes of American-made glass is shown in the following table: LIGHTS PER BOX ACCORDING TO SIZE Lights L ights Size per box Size pe :r box 7x 9 114 14x16 32 8x10 90 14x18 29 8x12 75 16x20 23 10x12 60 16x24 19 10x14 51 18x18 22 12x12 50 18x20 20 20x14 43 18x24 17 12x16 38 20x20 18 14x14 Zl 20x24 15 Plate elass is seldom used in commercial fe greenhouses, as its cost is prohibitive. It is but little better than A grade window-glass for this purpose. In conservatories where strength is more important than transpar- ency, fluted or corrugated glass, or glass in- 100 GREENHOUSES to which wire netting has been blown is sometimes used. Ground or frosted glass is occasionally used in palm-houses or ferneries, where a soft, subdued light is desired. This effect is more commonly obtained by paint- ing or whitewashing the clear glass and vary- ing the thickness of the coating according to the season of the year. Size of Glass. — The size of the glass varies according to the purpose for which the house is to be used, and the taste and personal pref- erence of the owner. Where extreme light- ness is wanted, large panes are used thus diminishing the number of sash bars. There is, however, a practical limit to the size. Glass increases rapidly in price as the size in- creases, and the large panes break more easily. Moreover, the size of the sash bars must be increased to carry the extra weight, and every increase in their size means more shade. Of 136 practical growers consulted on this point, 108, or. nearly 80 per cent., favored either 16 x 20 or 16 x 24-inch glass with the longer edge parallel to the sash bar. That is, the great majority preferred to have the sash bars spaced about 16 inches apart. GLAZING AND PAINTING 101 About 3 per cent, favored i6 x 20-inch glass with the shorter edge parallel to the sash bars, the bars in this case being 20 inches apart. Glass 16 x 20 inches is undoubtedly the most popular size. Methods of Glazing. — Practically all methods of glazing make use of putty to seal the glass in place and to form an air and water-tight joint. An exception is made when some forms of metal bars are used. With these, felt, candle wicking or some similar material is usually employed, and the glass is pressed firmly against it and kept in place by bolts or clamps. Sometimes a lead facing is used and the glass is clamped against this facing. The great majority of houses are con- structed with wood sash bars or bars having wood cores with which putty is supposed to be used. With these there are two common methods of setting the glass. It may be lapped or butted. Lapped Glazing. — In lapped glazing the lowermost panes in each run are laid flat against the bottom of the grooves in the sash bar. Each succeeding pane is then laid so that its lower edge laps over the upper 102 GREENHOUSES edge of the pane below it, in much the same way that shingles are lapped, except that the lap is much narrower. From one-eighth to three-eighth inches are allowed for lapping, the width of the lap depending somewhat on the size of the glass and the rigidity of the house and roof. It should be as narrow as possible, for little light passes through the lapped part of the roof. Fig. 57. — Lapped glazing Butted Glazing.— In butted glazing all panes lie flat against the bottom of the grooves in the sash bars, and the lower edge of each glass rests directly against the up- per edge of the one below. This form of glazing eliminates the lap, but it is more dif- ficult to secure a tight roof than when the glass is lapped. Roofs having a pitch of less than 30 degrees are likely to leak badly when the glass is butted. In this form of glazing the putty is some- times omitted, and the glass is held in place by wood caps which fit over the rabbets. When it is desired to make an especially tight' GLAZING AND PAINTING 103 roof, the upper and lower edges of the panes are sometimes dipped in a shallow tray con- taining thick paint. They are laid while the paint is soft, and in hardening this forms a tight, waterproof joint. Zinc glazing strips, bent in the form of a letter Z were at one time quite extensively used between the panes to make a tight joint. They are still used to some extent between the panes on side and end walls. Several advantages are claimed for butted glazing: (i) Less glass is likely to be broken by accidents, for if only one pane is hit, it only will be broken; while if the panes are lapped, the one immediately below is often cracked. (2) Less glass is broken by the ac- tion of frosts, as there are no laps in which moisture can collect and freeze. (3) The roof is lighter, as there are no laps to ob- struct the sunlight. The chief disadvantage, aside from leak- age, is the difficulty in repairing the roof when a glass is broken, for the pane must be cut to fit tightly. In cold, stormy weather, this is a slow and tedious process. Butted glazing is much less used than formerly among practical growers, which is proof that, in general, it is not so well suited 104 GREENHOUSES Fig. 58.— Putty knife for glazing roofs as is lapped glazing. More than 90 per cent, of the growers interviewed on this subject preferred lapped glass roofs. On side and end walls, glass is quite com- monly butted v/ith good results. Putty. — Putty is a pli- able substance used in set- ting glass. The principal ingredients are whiting and linseed oil, and its chief virtues are that it is easily worked and applied, and that it does not shrink on drying, thus making a water-tight seal. For greenhouse use, putty as bought in the gen era! market should be mixed with pure white lead at the rate of one part of lead to five of putty. This will stick to the bars and glass much better than will Fig. 59.— Machine for dis- ordinary putty. tributing putty GLAZING AND PAINTING 105 Putty purchased from dealers in green- house supplies will not need the addition of lead. It should be worked as soft as it can be handled in order that it may be easily forced into all cracks and crevices. It is applied with a putty knife or with a putty machine. The putty machine distributes the putty rather more rapidly than can be done by hand, but it is necessary to use a putty knife in conjunction with it. Setting the Glass. — The basic difference between glazing greenhouse roofs and glaz- ing ordinary window-sash is in the method of applying the putty. In glazing window- sash, the putty is placed on the outside. In greenhouse glazing the putty is placed in the Fig-. 60. — A, window glazing; B, greenhouse glazing The putty is shown at a and b grooves in the bars and the glass is forced into it. That which oozes up around the edges is scraped off and used again. By this method, little putty is exposed to the air, but 106 GREENHOUSES the glass is sealed by a thin film underneath and along the sides of each pane. This method has been developed because experi- ence has shown that on roofs putty soon checks and crumbles away when exposed to the weather as in window glazing. When glass is lapped, the following meth- od is used. First, the sash bars should have been so placed that the space left for the glass is about one-eighth of an inch wider than the glass. This provides room for the ''side putty." (For method of spacing see page 87). Sash bars are usually primed when re- ceived from the factory. They are given an- other coat of paint after they are put in place and are then ready for glazing. Glazing is started at the bottom of the run. A line of soft putty is first placed in the rab- bets and a pane of glass forced firmly into it until it is imbedded against the bar. A groove is usually provided in the plate to re- ceive the lower edge of this glass to prevent it from sliding down, but if there is no such groove, three or four brads or glazing points are driven for the lower edge to rest against. The excess putty is then removed and the next glass forced firmly into place, so that its lower edge laps over and rests firmly on GLAZING AND PAINTING 107 the top of the first, and its upper edge rests on the sash bar. This is fastened at the bot- tom with brads or glazing points to prevent its sUding down. The remaining panes of the run may then be placed in the same man- ner, special care being taken to secure the uppermost firmly in place with glazing points. This is necessary because it has no glass above it to hold it in place, and because it acts somewhat as a key to keep the others in position. It is best to finish each run from bottom to top before starting on a new run, in order that the putty may cement into a continuous mass. On high and wide roofs, however, it is sometimes advisable to glaze the lower half of the roof, then move the scaffolding and glaze the remainder. How to Estimate Putty. — The amount of putty necessary to glaze a roof may be esti- mated as follows: A pound of putty, when applied by an experienced workman, will reach about 15 feet along one side of a run of glass or about 7>^ feet along both sides. To estimate the amount of putty, therefore, multiply the length of the run in feet by the number of runs and divide by yVi. This will give the number of pounds required. The 108 GREENHOUSES amount required for the sides and gable may be found in the same way. An inexperienced workman will use somewhat more than this amount as there will be more waste. In glazing by the ''butted glass'' method, putty may or may not be used. When it is used, the method is very similar to that de- scribed above, except that much less is required, as the panes are crowded down to the bottom of the rabbet along their whole length instead of only at their upper end. Sometimes in glazing by this method no putty is used until after the glass is laid, and then a small quantity of liquid putty is forced down along the sides of the glass with a putty Pig. 61. — bulb. Usually when the glass is Putty bulb ]3|^i|-|-g(^^ j-j^^ h^Ts are surmounted by wood caps. In this system special care must be taken to fasten the lower pane, as the sliding weight of the entire run rests against it. Glazing Points. — Glazing points are used to hold the glass in place. They may be had in several forms and sizes. A good glazing point is easily driven, does not split GLAZIXG AXD PAINTING 109 the wood, offers as little obstruction as pos- sible to the brush in painting and does not rust. Small sizes suitable for glazing win- dow-sash in which the putty is placed on the outside are too small for greenhouse glaz- ing. Zinc points of various forms have been frequently used because of their free- dom from rust. The triangular point is prob- ably the most popular of the zinc points, and Fig. 62L — ^Types of glazing points is quite commonly used in window glazing. It is not well suited to greenhouse glazing on account of the difficulty of fastening the panes of glass with it so that the}' will not slide down : x^f. Probably the most used point in green- house glazing is the double-pointed staple. This is easily driven and when galvanized is not subject to rust. The best form of this type of staple is bent to an angle in the cen- ter, so as to fit over and hold the lower edee 110 GREENHOUSES of the pane from slipping lengthwise, as well as to hold it down in place. In lapped glazing only two double points are used for each pane, that is, one at each Fig. 63. — Glazing with double glazing points lower corner. The upper edge is kept in place by the bottom of the pane above it. Ad- ditional points are required for the lower- most and topmost panes in each run, and as some will be lost and destroyed, it is well to GLAZING AND PAINTING 111 figure on three points for each pane. An average of five of the small single points will be required for each pane. (P Fig. 64. — Glazing with single glazing points Precautions. — All sheet glass is slightly curved, a condition caused by the process of manufacture. When seconds or B orade glass is used, it w^ill sometimes be found that the panes will be so much curved as to make 112 GREENHOUSES it difficult to lay a tight roof. If this trouble is experienced, it will be of advantage to sort the glass and lay out each run on a smooth floor, placing the panes having a similar de- gree of curvature in the same run. By doing this a tighter and more satisfactory roof can be laid. Theoretically, the glass will resist more pressure if it is placed so that the curve will be up, that is, so that it will present a convex surface to the weather. If, on the other hand, it is placed so as to present a concave surface to the weather, the water will have a tendency to flow away from the sash bars and putty to the center of the runs. In ac- tual practice, these are relatively unimport- ant considerations, but all glass in the same run should have approximately the same curvature. Liquid Putty. — This is sometimes used for sealing cracks in old glazing or in glazing by the ''butted" method. It may be made as follows: Take equal parts by measure of white lead, putty and boiled linseed oil. First, mix the putty and oil thoroughly and then add the lead. If it becomes too thick, thin with turpentine. GLAZING AND PAINTING 113 Substitutes for Glass. — On hot beds and coldframes and sometimes on temporary greenhouses, some transparent material other than glass is used. The reason for this is that glass is both expensive and heavy to handle. The most common substitutes are cloth and paper treated so as to make them w^aterproof and semi-transparent. Some- times a firm but lightweight white cotton cloth is used with no treatment, but it does not admit light enough to permit satisfactory growth of plants for any length of time. Paper can seldom be used for more than one year. Cloth may, with care, be used for several seasons. The best results are secured by stretching the cloth or paper on rigid frames or sash on which wires have been drawn tightly across at frequent intervals to serve as supports. The author has had good success by simply painting the cloth or pa- per, after stretching it over the frames, with pure, light, boiled linseed oil. Bailey, in the "Farm and Garden Rule Book," gives the fol- lowing recipes: (i) Paste stout, but thin Manilla wrap- ping-paper on the frames. Dry in a warm place and then wipe the paper with a damp sponge to cause it to stretch evenly. Dry 114 GREENHOUSES again and then apply boiled linseed oil to both sides of the paper and dry again in a warm place. (2) Dissolve iH pounds of soap in a quart of water ; in another quart dissolve i/^ ounces of gum arabic and 5 ounces of glue. Mix the two liquids, warm, and soak the paper, hanging it up to dry. Used mostly for paper. (3) Take 3 pints pure linseed oil, i ounce sugar of lead, 4 ounces of white resin. Grind, and mix the sugar of lead in a little oil, then add the other materials and heat in a kettle. Apply hot with brush. Used for muslin. PAINTING Probably few other structures require as careful or as frequent painting as do green- houses. This is due: First, to the moist con- dition of the air in the house, which favors the decay of the wood ; and second, to the dif- ference in temperature between the outside and inside of the house, which often causes excessive contraction and expansion of the structural material. It is especially important that all joints in the framework be thorough- ly coated when they are put together, and that they be well painted in order to prevent GLAZING AND PAINTING 115 moisture from entering. As a rule, green- houses should be painted one coat both inside and outside every second year, and inside portions which are especially exposed to damxpness and shade should be painted every year, care being taken to see that they are perfectly dry when painted. Nothing has yet been found which will excel pure white lead and oil with a turpentine dryer for this purpose.* For the outside the mtense white may be softened by the addition of a little lampblack or other coloring material, but for the inside, colors are avoided, as they have a ten- dency to absorb light. Pure white is un- doubtedly best for interior painting. Greenhouse woodwork when received from the factory has usually been given a priming coat. By special arrangement it is often pos- sible to have it treated in a bath of hot lin- seed oil or creosote. The latter will make it *On this point commercial greenhouse builders do not agree. One of the largest firms in the country uses a paint containing 10 per cent, of French zinc and finds it the most satisfactory paint they have ever used. Another well-known firm after experimenting with lead and zinc in varying proportions has gone back to pure lead. The tendency of zinc paints is to crack and peel, and of pure lead paints to become chalky. 116 GREENHOUSES almost proof against decay, but since the joints must be coated with a thick paint when the house is erected, and as the wood- work is preferably white in order to make the house as hght as possible, the extra expense involved is hardly warranted. Creosote also has a somewhat poisonous effect on some greenhouse plants. If the woodwork has not been primed when received, it is preferably so treated be- fore it is erected. Either pure, thin linseed oil, or a mixture of oil and yellow ochre is used for this purpose. As soon as erected, the whole framework is painted inside and out before glazing. After glazing another coat is applied. Because of the frequent painting necessary, it is seldom advisable at the time of erection, to apply more than two coats in addition to the priming coat. Paints for Iron Work. — Ordinary paints which are used for wood may also be used on most unpolished metals. The oxidization of iron and steel, however, is likely to stain white paint, unless these metals are first given a coating to prevent it. A good paint for this purpose may be made by melting to- gether three parts of lard and one part of powdered resin. This is brushed on in a thin GLAZING AND PAINTING 117 layer while hot. As soon as it is dry, ordin- ary white lead paint may be applied with little danger of its becoming discolored. Shellac may also be used for the same pur- pose. Hot water and steam pipes cannot well be painted with lead and oil paints on account of the action of the heat. One of the most satisfactory treatments for heating pipes is to paint them with the so-called "aluminum" radiator paint. This is light in color but rather expensive. Paints which dry with a glazed surface are said to interfere with the radiating properties of heating pipes. A dull drying black paint sometimes recom- mended for this purpose is a mixture of lamp- black and turpentine, to which linseed oil is added not to exceed a fourth of the bulk of the mixture. Amount of Paint Required. — This varies according to the kind and condition of the surface to be painted, and to some extent with the kind of paint used. Painters usually figure that a gallon of mixed paint will cover 250 to 300 square feet of white pine or cy- press the first coat, and 350 to 400 square feet the second coat. 118 GREENHOUSES A general rule for determining the amount required is as follows: Divide the number of square feet of surface to be painted by 200, the result will be the number of gallons of liquid paint required to give two coats. Another is: Divide the number of square feet by 18. The result is the number of pounds of pure, ground, white lead necessary for three coats. Shading. — During the summer the heat becomes so intense in a greenhouse that some shade must be given if plants are to be grown satisfactorily. This may be accomplished by the use of muslin curtains in the inside of the house or by lath screens laid upon the roof. The most common method in com- mercial houses is to apply some kind of a coating to the outside of the glass which will be washed off by the late fall rains. Some form of whitewash is most satisfactory. The author prefers a wash made of fresh- ly-slaked stone lime and water, to which is added one part of common salt to four parts of lime. The salt is added after the lime is slaked. This is then strained and applied with a spray pump. It is usually necessary to apply this two and often three times dur- GLAZING AND PAINTING 119 ing the summer, but it comes off readily through the action of the fall rains and frosts and seldom requires the use of the scrub brush. Another paint sometimes used is com- posed of white lead and gasoline, just enough lead being used to make a milk-colored liquid. This may be applied with a brush or with a spray pump. It adheres much better than the wash mentioned above, but is open to the objection that it is sometimes neces- sary to do considerable hand work to remove it in the fall. A third wash sometimes recommended is made as follows : Slake a half bushel of stone lime. Strain and add a brine made of one peck of salt in enough warm water to fully dissolve it. Then add three pounds of rice flour, and boil to a paste. Then add a half pound of whiting and one pound of glue dissolved in warm water. Mix thorougfhlv and let stand for a few days, thin with water, and apply. This is the whitewash com- monly used for painting fences and build- ings and is very adhesive. For greenhouses it is applied in a very thin coat. Brackets. — In glazing and painting the 120 GREENHOUSES outside of a roof, a common means of sup- port for the workman is a plank supported by brackets resting on the sash bars or on every other sash bar. Glazing Ladder. — Another device used more in painting than in glazing is a ladder Fig. 65. — Glazing ladder used in glazing and painting made b}^ nailing cleats on one side of a plank for foot holds, and on the other side longer cleats so that they will rest across at least two sash bars and thus distribute the weight. The ladder is held in place by hooks which reach over the ridge. CHAPTER VIII VENTILATION AND VENTILATING MACHINERY Greenhouse ventilation has not yet been worked out with the same care and precision as has the ventilation of dwellings, public buildings, or even barns for the use of live stock. On the other hand, greenhouses are seldom or never built without some special attention being given to the question of ventilation, whereas, dwellings and even public buildings are often erected without any reference whatever to this important subject. This anomaly may be partly explained by the following facts: (i) The transpiration of l^lants is not so well understood nor is it so easily measured as is the transpiration of ani- mals. (2) Windows are necessary in dwell- ings and public buildings to admit light and they may be utilized, when necessary, to pro- vide ventilation. (3) In greenhouses, ventila- tion is not only provided for the purpose of 121 122 GREENHOUSES maintaining a supply of fresh air, but is utilized as a method of controlling tempera- ture and humidity. (4) Greenhouses, be- cause of their transparent roofs, are much more liable to sudden or violent changes in temperature (especially in days of alternate clouds and sunshine) than are dwellings, and the necessity for ventilation in order to equalize the temperature is evident. (5) Greenhouse plants are, as a rule, particular- ly sensitive to cold drafts, and ventilation cannot be left to the indiscriminate opening of doors. Systems of Greenhouse Ventilation. — There can hardly be said to be any well de- fined systems of greenhouse ventilation, as compared with the so-called systems of ventilation for public buildings. Greenhouse ventilation rests on the principle that warm air has a tendency to rise, and since the air within the greenhouse is considerably warm- er than that outside, during both summer and winter, the question of changing the air presents no serious problem. It is only necessary to provide a means for the warm air to escape. The cooler air from the out- side easily finds its way into the house VENTILATING 123 through the numerous small openings be- tween the panes of glass. Side Ventilation. — Side ventilation is of little service, except during the summer months, as the opening of these ventilators in winter would expose the plants to a direct Fig. 66. — Greenhouse showing A, side ventilators; B, overhead or roof ventilators current of cold air which would prove fatal. Side ventilating sash are usually hinged at the top and open outward and upward. Probably less than 50 per cent, of the com- mercial houses in the country are equipped with side ventilation, though it is often con- 124 GREENHOUSES venient in spring and summer. An in- genious method is sometimes employed in conservatories whereby the air is taken in from below the benches and is warmed by passing over the heating pipes. Thus the danger of injury to the plants is greatly less- ened. There is no evidence to show that there is any special benefit to be derived from these ventilators (Fig. 67). Overhead Ventilation. — During the winter practically all the ventilation of greenhouses is accomplished by means of overhead ventilators set in the roof at or near the ridge. These ventilators are in the form of sash hinged on the outside, and may be closed down tightly over the sash bars or opened to any degree desired. As the warm air naturally rises, the opening of these ventilators allows the warmest air of the house to escape, and fresh cool air to filter in through the crevices between panes of glass without causing excessive drafts. Experience shows that these ventilators need, to be relatively narrow and practically continuous along the whole length of the house, rather than intermittent, as the pres- ence of occasional large openings is more VENTILATING 125 126 GREENHOUSES likely to cause drafts of cold air. They are preferably glazed with glass of the same width as used for the roof and they should be placed so that the bars of the sash will be directly over the sash bars. Size of Ventilators. — No definite rule can be given as to the size of ventilators, as so much depends on the location and arrange- ment of the house, the kind of plants to be grown, etc. Experience has shown that where the ventilators are continuous along the entire length on both sides of the roof, the following sizes are sufficient. Size of house Width of ventilating- sash Up to 40 feet wide 24 inches Above 40 feet wide 30 inches This is the rule followed by most green- house builders. Methods of Hanging Sash. — Ventilating sash may be hung so as to open either at the top or bottom; that is, they may be hinged at the lower side so as to open out and away from the ridge, or they may be hinged at the ridge so as to open upward from the lower side. Both methods have their advantages and disadvantages. Sash opening at the ridge have the advantage that the air will VENTILATING 127 escape more rapidly when the ventilators are opened, as there is but little obstruc- tion and the opening is at the highest part of the house. There is also less tendency, when ventilators are used on one side of Fig. 68. — Two methods of hanging ventilator sash the roof only, for unfavorable winds to blow directly into the house. The practical disadvantages of this meth- od of hanging is that the ventilator sash are more likelv to be torn off bv severe storms than when hinged at the top, and also that it is more difficult to prevent leakage at the ridge. The prevailing tendency is to 128 GREENHOUSES hinge the sash at the ridge and in houses 30 feet wide or more to provide ventilators on both sides of the roof. Operating Machinery. — Since the ven- tilating sash are placed at the highest part of the house, and as it is necessary to change the size of the opening several times a day, it is obvious that it is highly desirable that some method be provided by which they may all be opened and closed from some point convenient for the operator. This is accom- plished by means of various types of sash- operating machiney. The essential features on which most types of ventilating machinery depend are as follows: (i) A horizontal shaft firmly fastened near the line of ventilating sash; (2) a system of gearing, by which power ap- plied at a point convenient to the operator may be transmitted to and rotate this shaft; (3) arms or levers attached to the shaft and also to the sash, and so arranged that the sash are raised or lowered when the shaft is rotated. Shafting. — The shafting generally used is one inch or one and a fourth inch gaspipe. The lengths are either riveted or clamped VENTILATING 129 together by special couplings so that the shaft will be perfectly rigid. A method sometimes used is to screw the lengths of pipe into an ordinary sleeve coupling as far as they will go; drill a hole through each end of the coupling and pipe, and rivet all together with tight-fitting rivets. This method is less satisfactory, however, than Fig. 69. — Malleable iron shaft couplings the use of split malleable iron castings sev- eral forms of which are to be had. These castings are longer and stronger than the usual sleeve coupling and they thus have a firmer grasp on the pipe. They usually have pins or lugs cast in the inside which fit into holes drilled in the pipe at the proper positions, and the two parts are clamped tightly in place by means of bolts. A special advantage of this meth- 130 GREENHOUSES od of coupling is that the shafting may be put up in sections and clamped together after being put in place. Square or round, solid shafting is sometimes used, but it has less torsional or twisting strength, weight for weight, than does good wrought-iron or steel pipe. Wrought pipe comes in two weights, standard and extra heavy. It is safe to use the different sizes and strengths as follows: Shafts up to 50 feet in length, I inch standard strength; shafts up to 75 feet in length, 40 feet of i inch extra heavy, and 35 feet standard strength; shafts up to 125 feet in length, i/4 inch all extra heavy. Shaft Hangers. — The shafting is held in place by means of hangers. These hangers Fig. 70. — Shaft hangers may be fastened to the rafters, to the sash bars or to the supporting posts. In iron frame houses it is customary to hang overhead shafting from the rafters and the shafting for the side ventilators from the side posts, using a hanger for each rafter or post. VENTILATING 131 When the shafting is hung from the sash bars a hanger is attached to every second or third bar, usually to every second. Fig. 71.- Open col- umn ventil- ator gearing i)«=5> ...fx. Fig. 12.- Open col- umn chain operated ventilator gearing Gearing. — Generally speaking, there are three types of gearing utilized for operating overhead ventilator shafting. These are: (i) The column gear, of which there are many different forms; (2) the chain-oper- 132 GREENHOUSES ated gear; and (3) the rack and pinion gear. In the column gear a post or column sup- ports the gearing and the wheel to which the power is applied. One form of column gear is known as an open column gear, because the drive rod is not inclosed in the column and there is no housing about the gearing. In another open column gear type a chain is used to transmit the power. In the closed col- umn types all gearing is inclosed and runs in oil, much the same as in the transmission case of an automobile. This insures free- dom from noise and ease of operation. In the chain type no columns are required, a feature much prized by growers. By this sys- tem practically all the ventilators in a house may be operated from one point, as the chains may be run almost anywhere in the house by the use of pulleys. The ab- sence of columns means less shade. The rack and pinion type differs from the two general types mentioned above, not so much in the method of applying the power Fig. 73.— Closed col- umn ventil- ator gearing VENTILATING 133 Fig. 74. — Chain system of operating ventilators. No columns used Fig. 75. — Rack-and-pinion system of operating ventilators 13i GREENHOUSES to the shaft as in the method of actually opening the ventilators. The chief advan- tage of this system lies in the fact that there is less torsional or twisting strain on the shafting than when the usual method is em- ployed, and they are more powerful. The chief disadvantage is that provision must be made for giving the shaft several revolutions, while a half or two-thirds revolution is usual- ly sufficient with the more common forms. Some practical growers claim that the rack and pinion device is very subject to wear and is a frequent cause of trouble. This is more especially true of the older forms of this type. The fact that they are not generally used would seem to indicate that practical growers as a rule are not yet convinced of their super- iority, though they are now being installed in some large houses where it is necessary to operate long runs. Quite frequently the hand wheel and gear- ing are fastened to the rafters or purlin posts and no extra columns are required. Side Ventilating Machinery. — The essen- tial features of side operating machinery are the same as for overhead ventilators. When there are side benches a shaft is VENTILATING 135 Fig. 76. — Ventilators (a and b) operated by means of rods twilh universal joints attached to posts and rafters. No extra columns are necessary. usually used and the hand wheel placed at a convenient position for the operator. When there are no benches along the sides a com- pact device is advisable in order to take up as little room as possible (Fig. 78). 136 GREENHOUSES Fig. n. — Device for operating side Ventilators Ventilator Arms. — Ventilator sash are most commonly raised and lowered by means of hinged braces or arms operated from the shafting. There are three general types. The elbow arm is most commonly used but has the disadvan- tage that a long lever- age is required, in order to open the venti- lators to the full width, which puts a consid- erable strain on the shaft. The double acting arm overcomes this dif- ficulty to some extent as it is possible to se- cure a wider opening with a shorter leverage, but it is necessary to rotate the shaft through an extra half turn. On long runs these arms are now being extensively used in place of the common elbow arm. The extending arm is used in low houses, or for side ventilators, or in other places where an elbow or double acting arm would extend into the house so far as to be in the VENTILATING 13T way. It folds together when the sash is closed and occupies little space, but it ex- tends automatically when the shaft is turned. It is especially convenient under certain con- ditions, but it lacks the strength necessary for long runs. Fig. 78. — Compact machine for operating side ventilators In all systems the arms are clamped se- curely and rigidly to the shafting, and as near as possible to the hangers so as not to spring the shafting when heavily loaded. They are spaced about 3 feet apart along the sash. If continuous sash are not used the arms should be distributed as follows: For sash up to 4 feet long, one arm ; from 4 to 7 138 GREENHOUSES Fig. 79. — Types of ventilator arms, A. double acting- arm; B, elbotw arm; C, extending arm closed; D, extend- ing arm open VENTILATING 139 feet long, two arms; and from 8 to ii feet long, three arms, etc. Capacity of Ventilating Apparatus. — The capacity of ventilating apparatus depends largely upon the size and method of manu- facture, but the length of run is limited to the torsional strength of the shafting. In long lengths there is always more or less tor- sion, so that the ventilators at the extreme end do not open as wide as those close to where the power is applied. This is of little consequence in summer when the ventilators are wide open, but in winter, when only slight ventilation is required, it may result in the sash at the end of the shaft not open- ing at all and the ventilation will thus be un- even and unsatisfactory. Moreover, the sash are likely to be frozen down in winter and the tendency for the shafting to twist is thus increased. It is wise to have a wide margin for safety. An indication of the length of shafting that may be used with safety is given on page 130. Tests show that one and a fourth-inch standard pipe has a torsional strength 42 per cent, greater than i-inch 140 GREENHOUSES double-strength pipe and that the weights are practically the same. The price of i- inch double-strength pipe averages about 25 per cent more than standard one and a fourth inch pipe. It is evident, therefore, that for long runs it is not only safer but more economical to use one and a fourth-inch standard pipe than i-inch double-strength. Generally speaking, a 150-foot run is about the limit when elbow arms are used. This may be slightly increased by using the double acting arms, and still further by us- ing the rack and pinion system. This is equivalent to saying that the ventilators in a house 300 or 350 feet long may be operated from one station by having machines located in the center of the house and operating each way. It is economy to have all ventilator sash for one house operated from the same station if possible. Sliding Shaft System. — In order to enable the operator to care for an extremely long line of sash from one station a sliding shaft system has been devised. In this case the shafting is solid and square, and instead of rotating it slides backward and forward, the motion being given by a pinion working on a screw or worm gear at one end of the shaft. VENTILATING 141 Fig. 80. — Sliding- shaft system for operating ventilators This sliding movement is utilized to operate the sash by means of a right angle lever, pivoted at the angle with the short arm attached to the shaft and the long arm to the sash. It is claimed for this system that it will operate a line of sash 500 feet long. CHAPTER IX BEDS, BENCHES AND WALKS In the earlier greenhouses, plants were al- most always grown on raised benches. This was partly for the convenience of the grow- er and partly because the houses were almost always erected with high, solid, side walls and it was necessary, in order to secure satis- factory growth, to bring the plants close to the glass roof. In modern houses, when all or part of the side walls are of glass, raised benches are not so necessary, and are very commonly dispensed with and the plants grown directly in the soil which forms the floor. This is particularly true when vege- tables such as lettuce, tomatoes or cucum- bers are grown. Florists, as a rule, have been loth to give up the use of benches and present the follow- ing arguments in their favor, (i) It is more convenient to care for plants when grown on raised benches than when grown on the ground. (2) Benches make possible 142 BEDS, BENCHES AND WALKS 143 O 2; ba G '% O bo JO 00 bib 144 GREENHOUSES the placing of the heating pipes underneath, which makes them less conspicious and at the same time affords a method of giving ''bottom heat/' which is considered advant- ageous with many plants. (3) It is main- tained that there is a better circulation of air about plants grown on benches and that the plants are less subject to disease. (4) The temperature and moisture of the .icil can be more easily regulated in benches. (5) Low-growing plants make a better dis- play when grown on benches. The following are the most common dis- advantages claimed by those who urge against the use of benches, (i) They are expensive to build and maintain. (2) They do not admit of an economical use of space. (3) The soil dries out rapidly. (4) The soil has to be changed more often. (5) It is more difficult to use labor-saving tools such as wheel-barrows. (6) All work must be done by hand. In large houses it is possible, when plants are grown on the ground, to pre- pare the soil with a horse or with wheel hoes. (7) With high-growing plants such as to- matoes and cucumbers, it is difficult to har- vest the crop when they are grown on high benches. BEDS, BENCHES AND WALKS 145 Fig. 82. — Tomatoes growing in solid raised beds Fig. 83. — Solid raised hods of hollow building tile in use at the Michigan Agricultural College A 146 GREENHOUSES Raised Beds. — To overcome some of the objections to raised benches, many growers use soHd raised beds, the height varying from a few inches to that common for benches. Such beds dry out less cjuickly than do benches, the soil does not have to be removed as frequently, and they are less expensive to maintain. They are open to some of the ob- jections urged against benches and do not possess many of the advantages afforded by culture in the open soil. The width and ar- rangement follows closely that of benches. Raised Benches. — Benches are exposed continuously to conditions which favor their rapid deterioration. Unless well constructed of good material, they are a source of con- stant annoyance. Many growers use wooden benches. Others use benches having iron frames, and sides and bottoms of wood, tile, slate or cement slabs. Still others use solid concrete benches. All forms have their ad- vantages and their advocates. Wood Benches. — Wood benches have the advantage of slightly less first cost, though if good material is used, the cost will be near- ly as great as for iron frame benches. In permanent houses nothing but cypress or BEDS, BENCHES AND WALKS 147 cedar should be used, genuine pecky cypress being undoubtedly the best. The sides and bottom boards are not less than i inch thick. The side boards are 8 inches wide. 11MI/H I B Fig. 84. — Two types of wood benches. A, bottom boards running lengthwise; B, bottom boards running crosswise The width of the bottom boards is imma- terial, except that when in place they have a space of a fourth-inch between them for drainage. They are usually run length- wise of the bed and are supported by cross- beams, spaced not more than 4 feet apart. The size of the cross beams will depend somewhat on the width of the bench, as follows: For benches up to 4 feet wide 2x4 inches For benches from 4 to 6 feet wide.... 2x6 inches For benches over 6 feet wide 2x8 inches The legs or posts are at least 4x4 inches in size, and rest on concrete or brick piers. Sometimes, when cement walks are used, they are made to extend under the benches far enough to act as a foundation for the posts. us GREENHOUSES To guard against warping of the side and end boards of wood benches, angle irons may be used in the corners and along the sides, and fastened by screws or small bolts. Brick piers may be used in place of the wooden legs. The wooden legs, however, will usually outlast the bottom boards and cross-beams. Fig, 85. — A type of iron frame bench Iron Frame Benches. — In the majority of iron frame benches, i-inch wrought-iron pipe is used. It is rarely threaded but is tied together with split malleable iron castings by the use of bolts and set screws. The sides and bottom may be made of wood, iron, slate, tile or even of cement slabs. All are BEDS, BENCHES AND WALKS 149 removable and may be replaced without tak- ing down the frame. Iron frame benches with cypress sides and bottoms are now much in favor. They are but little more expensive than the all-wood benches and are in most cases more satis- factory, as the frames are nearly indestruct- ible. They should, however, be made of wrought-iron pipe rather than of steel. They may be had in two forms, one in which the bottom boards run lengthwise of the bench and another in which they run cross- wise. The advantage of the latter is that short lengths may be used. These benches may be purchased with all parts cut to order, or they may be easily cut by anyone familiar with pipe cutting. Iron frame benches are also made of angle iron or structural iron of different forms. The chief disadvantage of these is that the iron cannot l)e worked readilv bv the ordin- ary workman and must be cut and fitted at the factory. Concrete Benches. — Concrete, because of its permanency, is often recommended for greenhouse benches, and its use is increas- ing. In general, there are two separate 150 GREENHOUSES BEDS, BENCHES AND WALKS 151 types. In one type the legs, bottom and sides are cast separately in molds and then put together in the greenhouse. In the other type the whole bench is cast in a form built in the house where it is to stand. There are at least two firms having patents on cement greenhouse benches and who are pre- pared to sell or rent molds or forms for mak- ing them. It is also possible for a skilled mechanic to make forms to suit any special location or for any form of bench. In mak- ing concrete benches, care should be taken to provide for adequate drainage through the bottom and to see that they are thoroughly reinforced. There has been some discussion as to the effect of concrete benches on the growth of plants. The author has had but little prac- tical experience with them but quotes from one of the largest users of concrete benches in the country, as follows: "At my place I use only concrete benches and the results and advantages .have been very satisfactory, but I want to be open and frank concerning the disadvantage, which is only for the first year. Something in the line of a chemical of a whitish nature ap- pears on fresh new cement, and that seems 152 GREENHOUSES to be injurious to plants; but after you have filled the benches with soil and used them the first year, the soil generally eats or ab- sorbs this chemical, and the roots of carna- tion plants or anythmg else cling to the ce- ment slabs the same as they do to slate. A good remedy to get rid of this so that it will not injure the plants is simply to put air- slaked lime or rather heavy whitewash on the inside of the bench, and that seems to protect the plants from coming in contact with the chemical mentioned/' Height and Width of Benches. — The height of greenhouse benches is largely de- termined by that most convenient for the operator to work. This in turn depends upon the nature of the plants to be grown. For example, when low-growing plants like lettuce are grown, a bench 32 inches high is about right ; but when carnations are grown this may be so high as to make disbudding difficult. This refers to the distance from the top of the walk to the top of the sides of the bench. The width of the" bench depends on the width of the house, on the arrangement of the benches, and to some extent on the kind BEDS, BENCHES AND WALKS 153 of plants to be grown. It is limited to the distance a man can conveniently reach in caring for the plants. This distance is about 2>^ feet or rarely 3 feet. In other words, benches that can be worked from one side onlv should be no more than 2>^ or 3 feet wide, and benches which may be worked from both sides should be no more Fig. 87. — Method of arranging benches in an uneven- span house to secure best advantage of the sunlight than 5>^ or rarely 6 feet wide. In uneven span houses it is sometimes advisable to ele- vate the walks and benches. Arrangement of Benches. — This is gov- erned by the width of the house, the use for which the house is designed, the height of the beds or benches and by the individual preference of the owner. Commercial grow- 154 GREENHOUSES ers look upon walks as waste space and en- deavor to keep them as narrow as is con- sistent with ease and economy in getting about the houses. In private houses, con- servatories and show houses, the walks are sufficiently wide to allow two persons to pass easily. 1 30- f — -5.- -5- Fig. 88. — An arrangement of benches in a 30-foot house. Only 66 2-3 per cent of the floor space available for crops In figures 88 and 89 are illustrated two methods of arranging benches in a 30-foot house. By the first method four benches, each five feet wide, are provided and 661 per cent of the floor space is available. By the second method three wide and two narrow benches are provided and 733 per cent of the floor space is available. In the latter method BEDS, BENCHES AND WALKS 155 the side benches extend the entire length of the house and one walk is eliminated. It is worth while to exercise considerable care in determining the arrangement of the benches, especially in commercial houses. As a rule a walk along the side of a house is an extravagance. When the width of the —Z>0' -^±- -;t --/-S"- Fig. 89. — Another arrangement of benches in a 30-foot house. By this arrangement 7Z 1-3 per cent of the floor space is available for growing crops house admits, it is usually more economical to have narrow benches along each side. When low beds are used, the walks may be narrower than with high benches as peo- ple can pass more readily. Tn conserva- tories and show houses 3 feet is none too 156 GREENHOUSES wide. In commercial houses with high benches, from 20 to 24 inches is a common width. When low beds are used, the walks are sometimes as narrow as 14 or 16 inches. It is often advisable to arrange the benches so as to have the center walk of ex- tra width, which will allow of the use of a wheel barrow or cart in removing and re- plenishing the soil and for other purposes. Material for Walks. — Concrete is unques- tionably the best material for walks. Water has no effect on it; it is substantial; it may be used as a foundation on which bench legs and ventilator columns may stand; and it may be quickly and easily laid. In conserv- atories and private houses nothing can take its place. For data on concrete construction see Chapter XIV. In commercial houses coal ashes are often used. Ashes must be kept away from the pipes as the sulphur they contain will cause the pipes to corrode very rapidly. Curbs. — For convenience and cleanliness, many growers who plant directly on the ground prefer to have their houses marked oft' into regular beds, divided by narrow walks and surrounded by a curb to keep the BEDS, BENCHES AND WALKS 157 soil in place. In time, the constant addition of manure raises the soil in these beds so that they become in reality raised beds. Board or plank curbs are rarely satisfactory, as the moisture of the soil on one side causes them to warp. The most satisfactory and economical curbs are made of concrete, which is heavily reinforced with iron rods when it is poured. CHAPTER X GREENI-IOUSE HEATING Generally speaking, there are only two satisfactory methods of greenhouse heating: Steam and hot water. Direct heating by stoves is not satisfactory even in small houses, and no satisfactory system has yet been devised for the use of hot-air furnaces. The only method aside from steam or hot water which deserves mention is heating by flues. They are wasteful of fuel, and their use is not justified, except in cheaply con- structed houses which are used only for a few months in the spring or fall. The principles pertaining to greenhouse heating are much the same as those involved in heating other buildings, except that the loss of heat is greater from glass than from wood or brick walls, and a higher and more constant night temperature is required than is necessary in dwellings. For this reason, relatively more radiating surface is required and boilers of larger capacity are needed. 158 GREENHOUSE HEATING 159 Heating with Flues. — In heating with fines the equipment consists simply of a furnace at one end of the house and a chim- ney at the other, the two being connected by a flue, carried underneath the bench or buried just underneath the soil, through which the heat and smoke are carried. This may be made of brick, but large-size drain or sewer tile are more commonly used. These withstand the heat and are easily and cheap- ly put in place. It is best to have the flue slope upward slightly toward the chimney. As has already been stated, this method is wasteful of fuel. It is also difficult to regu- late. It is still employed to some extent by vegetable gardeners in cheap houses, used only in late winter or early spring for the starting of early vegetable plants, sweet potatoes, etc. Hot Water vs. Steam. — There has been much discussion as to the relative virtues of hot water and steam for use in greenhouse heating. It may be well to consider here some of the advantages claimed for each. For hot water the followinof are claimed: (i) It provides a more even heat than steam. (2) The radiating pipes are not so hot, and 160 GREENHOUSES plants near them are less likely to be injured than when steam is used. (3) It requires less frequent firing, since warm water is al- ways circulating in the pipes as long as there is any fire in the furnace, whereas, with steam it is necessary to keep the water boil- ing to keep steam in the pipes. (4) For the above reason a night fireman is not required in small houses equipped with hot water. (5) It is less dangerous. This is more apparent than real, for steam is usually carried at low pressure. (6) It is claimed that hot water requires less fuel. Theoretically this should be true, but in practice it has not been very definitely proven. (7) Water will hold heat for some time if the fire should accidentally go out. The following advantages are claimed for steam: (i) Less cost of installation. (2) Steam requires fewer radiating pipes hence less shade is cast when the pipes are placed overhead than when hot water is used. (3) Less time is required to get up heat, as there is a relatively small body of water. (4) A greater area may be warmed from a given heating plant than with hot water, for the steam may be forced farther, (s) A steam GREENHOUSE HEATING IGl plant may be used to furnish steam for soil sterilization. All the above apply more especially to small ranges than to large ranges. As a rule, hot water is more generally used in ranges covering up to 20,000 square feet and steam in larger ranges, although there are many exceptions. At present the tend- ency seems to be toward the use of hot water rather than steam. In an investigation recently made by the author among a large number of greenhouse owners, 86 per cent, of those having 20,000 square feet or more under glass preferred steam heat. The chief reasons stated were, "better control," "cheaper maintenance," and "less shade from pipes." Six per cent, pre- ferred a combination of hot water and steam. The remaining 8 per cent, preferred hot water, stating as their reasons, "steadier heat," "plants grow better," "pipes do not rust out during the summer as with steam," and "cheaper to operate in spring and fall when little heat is required." Of those having less than 20,000 square feet under glass, 74 per cent, preferred hot water, giving in addition to the reasons 162 GREENHOUSES o .- 5 c 0\ u. l^ cS GREENHOUSE HEATING 163 named above, ''less labor to fire, especially at night" and "needs no night fireman/' Combination Systems. — A combination of hot water and steam may often be used to advantage. By this means steam may be had for power and at the same time be util- ized for heating. In cold weather both boil- ers may be used for heating, while in mild weather the steam boiler alone may be used, thus furnishing the necessary heat and power. Another and more simple combination of hot water and steam heating which, how- ever, is more expensive in installation, con- sists of two separate sets of heating coils, one of which is connected with a steam boil- er and the other with a hot water boiler. The steam is used when a small amount of heat is needed quickly on cold nights in early fall or late spring, and to supplement the hot water in severe winter weather. In any system of heating it is much safer, as well as more economical in operation, to install two or more boilers rather than to depend on one large one. Both may be used in severe weather and in case of acci- dent to one, the other may be forced for a 164 GREENHOUSES few days and thus protect the plants from injury by freezing, which would inevitably result if only one boiler was in use. Heating Coils. — Because of the large amount of heating surface required, and be- cause all parts of a greenhouse must be kept at as nearly uniform temperature as possible, radiators such as are used in private houses have not been found practicable in green- house heating. Instead, long coils of wrought iron or steel pipe are used. For steam heating these coils are commonly of I or iM-inch pipe. In hot water heating they are slightly larger, varying from i/4 to 2 inches. In the early days of hot water heat- ing large cast-iron pipe, often as large as four or five inches in diameter was used. It is still used to some extent, but more often in small private conservatories than in com- mercial houses. There is very little to be said in favor of using cast-iron pipes. The fact that they are now so little used shows that they have no special merit. The smaller, wrought pipe is lighter and much more easily handled; is screwed together instead of caulked "with lead and oakum; has much more radiating GREENHOUSE HEATING 165 surface in proportion to the volume of water contained; can be placed along the side walls or hung on the supporting posts in- Fig. 91. — Under-bench heating with large cast-iron pipes stead of having to be supported on mason- ry piers ; and permits of a more perfect con- trol of the heat. 166 GREENHOUSES Heating coils are made by joining several pipes together by means of headers. The hot water is conducted to the coils from the boiler by means of a larger pipe known as a flow pipe or feed pipe. It is returned to the boiler by means of a return pipe. In steam heating the coils are often so arranged that the water formed from the condensed steam returns to the boiler through the flow or feed pipe, instead of through a separate return pipe. ,. j.'" CHAPTER XI HOT WATER INSTALLATION General Principles. — Before discussing the installation of a hot water heating sys- tem it is necessary to have in mind the phy- sical and mechanical principles involved. Briefly they are these: Water increases in volume as it is heated and it is consequently Hghter in weight. When a fire is lighted un- der a water boiler the water around the heat- ing surface expands and, being lighter, is forced upward by the heavier, colder water. Popularly speaking, the hot water ''rises." The practical problem is to conduct the hot water from the boiler to the coils where the large radiating surface permits the water to give up its heat to the air in the house and then, as it becomes colder and heavier, to conduct it back to the boiler where it will displace the warmer and lighter water there. Gravity is the force utilized to produce cir- culation. It acts with a force proportional to the difference in weight between the col- umn of warm water and the column of cool water. 167 168 GREENHOUSES The following table shows the weight of a cubic foot of distilled water at different temperatures. 32 degrees F.. 62.42 pounds 170 degrees F.. 60.77 pounds 100 ....62.02 " 180 ..60.55 110 ....61.89 190 ..60.32 120 ....61.74 200 ..60.07 130 ....61.56 " 210 ..59.82 140 ....61.37 " 220 ..59.76 150 ....61.18 " 230 ..59.37 160 ....60.98 '• From the above table it is apparent that a cubic foot of water entering the boiler at 140 degrees is 0.82 pounds heavier than an equal quantity leaving the boiler at 180 degrees. It is evident that the higher the columns of water the greater will be the difference in weight, and consequently the more rapid will be the flow. The various factors influencing the veloc- ity of water in a gravity hot water system are embodied in the followingf formula. 'fe Y^^ / 2gh (w— W) V (w+W) In this formula, V=the velocity in feet per second, g=the force of gravity (32.16), h= the total height of the system, W=the weight of a cubic foot of water wdien it leaves the HOT WATER INSTALLATION 169 boiler and w=the weight of a cubic foot of water when it enters the boiler. This, of course, disregards friction. The practical application is that when it is de- sired to increase the velocity of the water; e.g. in long runs, it may be done by either lowering the boiler or by raising the height of the flow pipes. The following table shows the velocity in feet per second in a hot water system under various conditions. Height Difference in temperature on leaving and of entering boiler Column 5° . 10° 15° 20° 30° 40° Feet Per second 5 ft. 0.541 0.750 0.922 1.09 1.33 l.Sl 10 " 0.765 1.06 1.32 1.55 1.88 2.04 20 " 1.085 1.50 1.85 2.19 2.66 3.01 30 " 1.35 1.83 2.26 2.68 3.26 3.71 Arrangement of Piping. — There are two approved methods of arranging the piping for hot-water heating. One is known as the ''down hill"; the other as the ''up hill.'' In the former the highest point in the system is directly above the boiler. In the latter the highest point is at the end of the system farthest from the boiler. Either is satisfac- tory and is preferred to the "level" system sometimes advocated. In either the "down 170 GREENHOUSES hill" or the "up hill" system the air which collects in the pipes will eventually reach the highest point when it may be allowed to escape through an automatic air valve. In the "level" system slight sags and raises are likely to occur and the air will collect in the higher parts and cause trouble. Fig. 92. — Diagram showing "down-hill" and "up- hill" systems of piping. A, boiler; B, flow pipe; C, C, headers; D, radiating pipes or coils; E, re- turn pipe; F, automatic air valve; x indicates height of water column The author prefers the "down hill" system when the flow pipes are carried in the upper part of the house and the coils are consider- ably lower. When all the pipes must be in the lower part of the house, or under the benches, he prefers the "up hill" system. The HOT WATER INSTALLATION 171 Fig. 93. — A type of automatic air valve majority of greenhouse oper- ators seem to be in accord with this view. Practically speaking there appears to be but little difference in the efficiency of the two systems and the convenience and the arrangement of the house de- termines the choice to a con- siderable extent. Estimating Radiation. — The calculations for green- house heating are based on certain fundamental facts which for hot water may be stated briefly as follows: A square foot of glass will give off, under or- dinary greenhouse conditions in winter weather, approximately i B. T. U-"^ of heat per hour, for each degree difference in tem- perature between the air inside the green- house and that outside. A good wood, brick or concrete wall will give off about a sixth as much, or a sixth B. T. U. per square foot per hour. It is customary to divide the total wall surface by six and consider it as equiva- lent to glass. *British Thermal Unit; the amount of heat required to raise one pound of distilled water from 62 to 63 degrees F. 172 GREENHOUSES To arrive at an estimate of the possible heat loss from a greenhouse add to the total square feet of exposed glass surface a sixth of the total square feet of exposed wall sur- face, and multiply the sum by the difference between the temperature at which the house is to be kept and the lowest outside tem- perature which will probably be experienced. Suppose, for example, that a house has 10,000 square feet of glass and equivalent glass, that it is desired to keep it at a night temperature of 50 degrees, and that the low- est outside night temperature to be expected is — 10 degrees. The number of B. T. U. given off by such a house under these con- ditions would be [50° — ( — 10°)] x I X 10 x 10,000 or 600,000 B. T. U., and enough heat- ing coils must be provided to supply this amount. In hot water heating the coils will give off approximately two B. T. U. per square foot of surface per hour for every degree difference in temperature between that of the coil and that of the surrounding air. The average temperature of the coils may be taken to be 160 degrees, and if the house is to be maintained at 50 degrees the difference will be no degrees. Multiplying no by 2 HOT WATER INSTALLATION 173 we have 220 or the number of B. T. U. given off by each square foot of radiating surface per hour. If, then, we divide 600,000 by 220 we have 2.,y2y which is the number of square feet of radiating surface to be pro- vided. These principles may be embodied in the following formula where R= the amount of radiating surface required in square feet; T, the temperature to be maintained inside the house; t, the lowest outside temperature to be expected; and G, the number of square feet of glass and equivalent glass. ^^(T-t) X G (160-T) 2 This formula gives a wide margin of safe- ty. Most builders prefer to use consider- ably less radiating surface and depend on forcing the furnace in extremely cold wxather. By so doing the temperature of the coils may be kept at 180 degrees or even considerably higher under favorable condi- tions and the amount of radiation required will be correspondingly less. Amount of Pipe Required. — Having esti- mated the amount of radiation required the next problem is to find the quantity of pipe 174 GREENHOUSES necessary to provide this amount. For ex- ample, I linear foot of i>^-inch pipe furnishes about half a square foot of radiating surface. Divide the number of square feet of radia- tion required by the outside area of a linear foot of pipe of the desired size. The result will be the number of linear feet of pipe re- quired. From this is subtracted the amount of radiation supplied by the flow or feed pipe and other fittings. The following table gives the radiating area in square feet of a linear foot of pipe of various sizes. Size of pipe Radiating surface of 1 linear foot 1 1^ 1/2 2 3 3/2 4 inch 0.27 square feet 0.35 0.43 0.49 0.62 0.75 0.91 1.05 1.18 For practical purposes the following gen- eral rule will give approximately the amount of radiating surface required. Divide the number of square feet of glass and HOT WATER INSTALLATION 175 equivalent glass: By 6 to heat the house to 40 degrees By 4 to heat the house to 50 degrees By 3.5 to heat the house to 60 degrees By 3 to heat the house to 70 degrees The quotient will be the square feet of radiating surface required. Size of Flow Pipe. — Having determined the amount of radiation necessary, the next problem is to determine the size of the flow or feed pipe required to supply the coils. Experience has shown that it is not necessary for the supply pipe to be equal in capacity to the sum of the capacities of the coil pipes. The correct size may be determined, theo- retically, by the use of the following rather tedious formula: A=. ^^ 25wvt In this formula A=the cross section area in square inches of the flow pipe; H, the total radiation in B. T. U. per hour given off by the coils; R, the radiating surface in square feet; w, the weight of the water per cubic foot; v, the velocity of feet per second; t, the difference in temperature between the water when it leaves the boiler and when it returns. This formula is seldom used but the fol- 176 GREENHOUSES lowing table has been derived from it. To use, measure the height of the water column in feet, find from the table the factor for this height, and multiply the square root of the radiating surface in square feet by this fact- or. The result will be the size of the flow pipe, in inches (diameter) required. This is based on the assumption that there is a difference of lo degrees in temperature be- tween the water when it leaves and when it enters the boiler. Height of Column (ft.) Diameter Factor 5 0.133 10 0.113 15 0.104 20 0.095 25 0.091 30 0.187 For example, to supply a coil of ten ij^- inch pipes lOO feet long (500 square feet) 15 feet above the bottom of the boiler, would require a feed pipe the diameter of which would be represented by V500 x 0.104 equals 22.4 X 0.104 equals 2.33 or a 2i/2-inch pipe. Short Methods. — The above formula takes into consideration the fact that the greater the height of the column of water the more rapid the flow and consequently HOT WATER INSTALLATION 177 the smaller may be the supply pipe used. In greenhouse heating, however, the height is seldom very great, usually varying between 8 and 20 feet, so that the following rule of thumb usually proves satisfactory. The flow^ pipe should be one pipe size greater in dia- meter (inches) than the square root of the radiating surface of the coil (in square feet), divided by 10. Applying this rule to the above problem we have V 500 -^10=^2.24 The next pipe size is 2/4 inches but this is so close to the estimated size that a 2>^-inch pipe should be used to insure efficiency. The size of the main supply pipe from the heater is determined in the same manner by taking the sum of all the radiating surface to be supplied. It is better to have one main flow pipe leading from the boiler, from which branches to the various coils may be taken, than to have a flow pipe direct from the boiler for each coil, though two or more flow pipes may be taken ofif. The return 1 pipes should be of the same size as the flow pipes. The flow pipe is taken from the top of the boiler and the return pipe enters at the bottom. In Fig. 94 is shown a diagram of a method for piping a medium-sized house. In the dia- 178 GREENHOUSES Fig. 94. — ^A method of piping a medium size house gram A is the flow pipe extending directly up from the boiler; B, B, branch flow pipes; C, C, branch flow pipes extending the length of the house; D, D, distributing pipes at the opposite end of the house; E, E, E, E, the re- turn coils; F, F, F, F, return pipes; and G, expansion tank. Valves should be conveniently placed so that any or all of the coils may be cut off in- dividually. They may be placed either in the flow or return pipe, or in both. If there is a valve in both the supply and return from each coil, any one may be repaired in case of an accident without drawing the fire or inter- HOT WATER INSTALLATION 179 ?^ ^ Fig-. 95. — Diagram showing under-bench method of hot water piping. A and B flow pipes; C and D heating coils fering with the circulation in the other coils. The valves should be of a type which, when open, cause as little resistance to the flow of water as possible. Length of Coils. — The length of the coils which may be used depends: (i) Upon the height of the column of water; (2) upon the size of the pipes which make up the coils; and (3) the amount of friction in the coils and fittings. The length of coils which may be satisfactorily used with pipes of various sizes are given in the following table. 180 . GREENHOUSES Size of pipe Length of coil 1 inch Up to 50 feet 1^ inch 50 to 75 feet V/2 inch 75 to 100 feet 2 inch 100 to 150 feet This table is based on the supposition that gravity, only, is to be depended upon for circulation. When pumps are used to cir- Fig. 96. — Gasoline engine arranged to circulate hot twater in a greenhouse heating system HOT WATER INSTALLATION 181 culate the water the length may be materially increased. The most commonly used size is i/^-inch, and when the houses are much over lOO feet in length two or more coils may be used, each extending only a part of the length, and having separate feed and return pipes. Expansion Tank. — Water expands in heating. It is necessary, therefore, to make some provision to take care of the expan- sion, in order that the pipes shall not burst and to keep them full at all temperatures. This is accomplished by connecting the sys- tem with an expansion tank into which the excess water will flow as it expands, and from which it will flow back into the system as it cools. It is placed at or above the high- est point in the system, but it may be con- nected with any part of the system or even with the boiler. The size of tank required is directly proportional to the volume of water con- tained in the system and is determined by the amount of expansion resulting from heating. The following table adapted from Kent shows the relative amount of expansion. 182 GREENHOUSES Temperature Cent. 4° 10° 20° 30° 40° 50° 60° 70° 80° 90° Temperature Fahr. Comparative Volume 39.1° l.OOOOO 50. ° 1.00025 68. ° 1.00171 86. ° 1.00425 104. ° 1.00767 122. ° 1.01186 140. ° 1.01678 158. ° 1.02241 176. ° 1.02872 194. ° 1.03570 100' .212. 1.04332 From the above table it will be seen that the increase in volume from 50 to 212 de- Fig. 97. — Automatic expansion tank. This is con- nected with the city water system and will auto- matically keep the heating system filled. See also G, Fig. 94 HOT WATER INSTALLATION 183 grees is 1.04432 — 1.00025=0.04307, or a little more than 4 per cent. It is customary to make the expansion tank large enough to hold 5 per cent, or a twentieth of the water contained in the system, including the boil- er. Thus, if the system contains 100 gal- lons, the supply tank should be large enough to hold a twentieth of that amount or 5 gallons. The capacity in gallons of a linear foot of standard wrought pipe is shown in the fol- lowing table. Size of pipe Capacity per diam. in inched linear foot 1 0.1408 gallons VA 0.0638 VA 0.0918 2 0.1632 2y2 0.2550 3 0.3672 4 0.6528 5 1.0200 6 1.4690 Pressure Systems. — Water in an open kettle cannot be heated above 212 degrees at sea level. At that temperature it boils and all further heat energy is expended in vapor- izing the water. In an open hot-water heat- ing system the same is true, except that the 184 GREENHOUSES slight pressure of the column of water in the system may permit the water in the boiler to reach a temperature slightly above 212 de- grees. If water can be kept under pressure it may be raised to almost any desired tempera- ture, and in a heating system this would mean less necessary radiating surface. The boil- ing point of water under various pressures above normal or atmospheric pressures is shown in the following table: Pounds pressure Normal Boiling point .212.0° Fahr. 1 2 3 4 5 6 10 pound 2137° " 215.3° " 218.5° 221.5° " 224.4° " 227.1° : 229.7° " 240.0° Several systems have been evolved to pro- duce pressure in a heating system. One of the earliest was the closed tank system in which the expansion tank was made air-tight and fitted with a safety valve set so as to let the air in the tank escape at a certain pres- sure. By this means the water in the coils may be made to reach a temperature con- siderably above the boiling point. HOT WATER INSTALLATION 185 Recently various automatic devices using a column of mercury to produce the same re- sult have been placed on the market. One model is designed to be placed in the pipe leading from the return pipe to the expansion tank, the tank in this case being open. The advantage of these devices over the closed tank system lies in the fact that they are less likely to become clogged and stick than are the safety or pop valves. In action these so-called ^'generators" operate as follows: The pressure is determined by the height of the column of mercury- When there is no heat in the boiler the mercury is in the position shown at a, Fig. 98. As soon as the water becomes warm it ex- pands and flows in through the opening x. This forces the mercury down in the cistern and up through the small pipe b. The amount of mercurv is so arrano^ed that when it is pushed down to the level of the Fig. 98.— A of mercury crator" type 'gen- 186 GREENHOUSES curve in the outlet pipe at c it overflows at d. This allows some of the water to escape, and this goes up through the pipe e to the ex- pansion tank, but the mercury being heavier falls back again through f to the cistern. This automatically keeps the pressure at any predetermined point, usually about lo pounds, which makes possible the heating of the water to a temperature of 240 degrees. This makes practical the heating of the coils to a high temperature in severe winter weather and at the same time permits the system to be run at lower temperatures in mild weather. In this respect it has the ad- vantage over steam. It is claimed for these mercury "generator" devices that they greatly improve the circulation of the water in a heating system. The most apparent advantage is that they make possible the use of less radiating sur- face, hence the first cost is less. It is but fair to say that, as a rule, growers who have installed them have found them satisfactory. When the hot water is circulated by pumps it is possible, though probably not de- sirable to maintain a high pressure. Econ- omy in heating by hot water lies in having abundant radiating surface and rapid circu- ! HOT WATER INSTALLATION 187 lation and then keeping the water at a mod- erate temperature. Caution. — In any system see that the ex- pansion tank and the pipe leading to it are placed where they will not freeze. As there is ordinarily no circulation in the water they contain they will freeze if placed where the temperature falls below freezing. The re- sults will almost surely be disastrous. CHAPTER XII STEAM INSTALLATION* General Principles. — In steam heating there is no circulation in the same sense that there is in hot water heating, but the steam is conducted into the heating coils,, where it condenses. In condensing it gives up its "latent'' heat. The water of condensation, which occupies only about 0.017 part of the space occupied by the steam, finds its way back to the boiler either by flowing back through the supply pipes, or through return pipes connected with the opposite ends of the coils. The latter system is most commonly used in greenhouse heating. In contrasting steam and hot-water heat- ing it is well to keep in mind the fact that only 180 B. T. U. are required to raise one *In order to avoid repetition steam- heating is- discussed largely in contrast to hot water 'heating, as described in the preceding chapter. Both chapters should be read by one wishing to inform himself on steam heating. 188 STEAM INSTALLATION 189 pound of water from 32 to 212 degrees but that 966 B. T. U. (usually considered as 1000) are required to change a pound of water at 212 degrees into steam. When the steam is condensed in the coils it gives off this heat. This is known as the latent heat of steam. It may be defined as the amount of heat ab- sorbed in changing from a liquid to a vapor or the amount given off in changing from a vapor to a liquid state. The problem in steam heating is to supply an amount of radiating surface sufficient to condense enough steam to furnish the amount of heat required. Under ordinary greenhouse conditions a square foot of steam radiating surface may be counted on to con- dense approximately one quarter pound of steam per, hour. Each square foot of radi- ating surface will, therefore, provide a fourth of 960 or approximately 240 B. T. U. per hour. The number of B. T. U. required per hour to heat a given house (see page 172), divided by 240 will give, therefore, the number of square feet of steam radiation required, and from the table on page 174 the number of linear feet of pipe may be easily determined. Assuming a steam pressure of five pounds 190 GREENHOUSES per square inch the following rule will be found useful in determining the amount of steam radiation required for a house when the lowest outside temperature to be ex- pected is not lower than zero. Divide the num'ber of square feet of glass and equivalent glass. By 9 to heat house to 40 degrees By 7 to heat house to 50 degrees By 6 to heat house to 60 degrees By 5 to heat house to 70' degrees The quotient will" be the number of square feet of radiating surface required Size and Length of Coils. — -There is less friction in steam than in hot-water heating, and for this reason smaller pipes may be used in the heating coils. They are seldom larger than 1%-inch, and i%-inch is very commonly used. Even i-inch pipe may be used in comparatively short runs. Smaller pipes may also be used in steam than in hot-water heating, for the rjeason that the radiation per square foot of surface is greater and there- fore less surface is required. In other words, an equal number of smaller pipes or a small- er number of pipes of equal size may be used in steam than in hot-water heating. Small pipes furnish a greater amount of radiation in comparison to their cubic capacity than STEAM INSTALLATION 191 do large pipes. Large cast-iron pipes are almost never used in steam heating. When i-inch pipe is employed coils may be safely used up to 75 feet in length; ij4- inch up to 150 feet; and i>^-inch up to 250 feet. As with hot water, better results and a more uniform temperature may be secured by using two or more comparatively short coils, rather than one which is excessively long. In small houses it is possible to run the coils entirely around the house, maintain- ing an even downward slope. Arrangement of Coils. — As indicated in a preceding paragraph, either of two methods of piping may be used. In one the water resulting from the condensation of the steam Fig. 99. — A corner coil. It allows for expansion of the pipes 19'2 GREENHOUSES flows back to the boiler through the supply pipe. In this case all pipes have an upward slope from the boiler, with no sags or pock- ets in which the water can collect. This method, sometimes known as the single pipe system, is very commonly used in heating dwellings where the pipes are mostly verti- Fig. 100. — A mortise coil designed to allow for expan- sion of pipes cal, but in greenhouses having long, nearly horizontal coils there is likely to be much hammering in the pipes, caused by the in- terference of the steam with the return water. A more satisfactory method for green- house heating is to arrange the pipes much the same as in hot-water heating, pro- portioning the size to the supply and re- STEAM INSTALLATION 193 turn pipes according to directions given in a following paragraph. This is known as the tw^o-pipe system. The return pipe en- ters the boiler below the surface of the water. The coils should have a fall toward the boiler of about I inch to 20 feet. It is not wise to use the straight coils commonly used for hot water in steam heating as they do not allow for the unequal expansion of the pipes when the steam is turned on quickly. In steam heating special form of coils are com- monly used among which are the corner coil and mortise coil. Size of Supply and Return Pipes. — Theo- retically, the size of the flow and return pipes in steam heating may be much smaller than in hot-water heating. This is especially true of the return pipe, since the water which it carries occupies only 0.017 of the space oc- cupied by the steam from which it is con- densed. In practice, however, the flow or supply pipe for steam is made nearly as large as for hot water and the return pipe only slightly smaller. The following table shows the flow of steam in pipes of different sizes at a pressure at the boiler of approximately five pounds. 1»4 GREENHOUSES Size of pipe VA inches 2 2/2 3 3-/2 4 A-y, 5 6 7 Pounds of steam per hour 70 138 220 390 570 800 1000 1400 2200 3200 To find the size of supply pipe required it is only necessary to determine the number of pounds of steam condensed per hour by the coils (approximately one-quarter pound for every square foot of radiation) and from the above table select the correct size. The following table, adapted from Carpen- ter, gives the size of supply and return pipes recommended to be used in the two-pipe sys- tem for different amounts of radiation, when a pressure of not greater than five pounds is used. Sq. ft. of radiation to be supplied Size of supply pipe Size return pipe 200 VA inch 1% inch 400 2 " VA 700 2-^ " 2 1000 3 " 2 1600 y/2 " 2A 2300 4 " 2A 3200 4-y2 " 2y2 STEAM INSTALLATION 195 4100 5 (( 3 6500 6 << 3 9500 7 << 3/2 Valves. — In steam heating it is essential that each coil be provided with a cut-off valve. This is even more essential than with Fig. 101. — Reducing valve 19G GREENHOUSES hot water since with steam heating the tem- perature of the steam must be at least 212 degrees, while with hot water the tempera- ture may be varied according to the weather. Automatic air valves are placed at the high- est point of each coil and also in the supply pipes. High Pressure Heating. — When steam above five pounds pressure is used it is known as high pressure heating. For greenhouse purposes high pressure heating is not satis- factory, as the pipes are too hot. In large establishments, however, a high press- ure is often maintained at the boiler and is passed through a reducing valve before it enters the coils. Vacuum and Vapor Systems. — Several heating systems are now on the market which endeavor to give to steam heating some of the advantages claimed for hot water, viz., a lower temperature of the heating pipes and less frequent attention to the boiler. They dififer from straight steam heating in that a partial vacuum is maintained within the system, thus causing the water in the boiler to give off vapor at a temperature of less than 212 degrees. STEAM INSTALLATION 197 There are several different systems but they may all be grouped roughly into three classes: (i) Those in which a vacuum is created by means of a pump or other me- chanical device; (2) those in which the air is expelled by raising the steam to a relative- ly high pressure, and then preventing it from returning by some form of automatic mer- cury seal, and (3) those in which a constant, though slight, vacuum or tendency to vac- uum is maintained, by connecting the sys- tem with the chimney and utilizing the "pull" of the draft. These systems are now being rapidly in- stalled in public buildings and dwellings, and no doubt will be found more satisfactory than steam for greenhouses. In addition to the advantages given above it is claimed for these systems that they are more economical of fuel than are either steam or hot water, that the circulation is better and surer, and also that there is no trouble arising in long runs from water of condensation. Arrangement of Boilers. — In the common gravity system of steam heating the boilers must be below the level of all mains and coils. When thev cannot be so located, 198 GREENHOUSES special devices to be described later must be employed to return the water of conden- sation. As with hot water, two or more boilers should be provided, rather than one large one, to allow for repairs in case of ac- cident and for use in severe weather to avoid the necessity of forcing. Steam Pumps and Traps. — As suggested in the preceding paragraph, it is sometimes impossible or inconvenient to place the boil- er below the level of the heating coils. This is especially true in large establishments, re- quiring large boilers using large quantities of fuel. In order to return the water of con- densation in such cases steam return traps and steam pumps are used. Their use is al- so necessary where a higher pressure is car- ried at the boiler than in the coils. The return trap is a contrivance which is automatic in its action, and which overcomes the back pressure from the boiler by an in- genious method of equalizing the difference in pressure between the boiler and the coils. Being automatic in its action and requiring but little attention it has been quite gener- ally used. Steam pumps, on the other hand, require considerable attention, though they STEAM INSTALLATION 199 are less complicated than the return traps. A small, separate boiler is generally used to operate the pump, and the exhaust and sur- plus steam is turned into the general heat- ing system after being reduced to low pres- sure. Gas and electric motors are also used to drive the pumps for returning the water of condensation. Fig. 102. — A type of steam return trap CHAPTER XIII BOILERS, FUELS AND FLUES The terms boiler and heater as used in dis- cussing greenhouse heating systems are synonymous. It is customary, however, to speak of a steam heating apparatus as a ''boiler" and of a hot-water heating appar- atus as a "heater," probably because in steam heating the water boils, while in hot-water heating it is not supposed to boil. It often occurs, however, that the same kind of heat- ing apparatus is used in both steam and hot- water heating with no essential changes, ex- cept in the accessories. In this chapter the term boiler will be applied to both steam and hot-water heating devices. The boilers used in greenhouse heating differ but little from those used in heating other buildings. In fact the same makes and styles of boilers are very frequently used for both purposes. Certain manufacturers have, however, made a thorough study of greenhouse heating and have developed boil- 200 BOILERS, FUELS AND FLUES 201 ers with this particular end in view. In buying a boiler the safe plan is to purchase a style which has fully established itself on the market and which is made by a thorough- ly reliable firm. Such boilers will have passed the experimental stage and repairs may be secured quickly and reasonably. Essentials of a Boiler. — The function of the boiler is to extract the latent heat from the fuel and transfer it to the water or steam, which may be circulated when needed. The essentials are, a grate on which the fuel is burned and a watertight receptacle, so ar- ranged as to present a large amount of sur- face (known as fire surface) to the fire or burning gases. The problem of the manu- facturer is to so arrange and proportion the fire surface and the grate surface that the heat of the burnins: fuel mav be most econ- omically absorbed and distributed. Grate Surface. — For best results the amount of grate surface should be large enough, so that the fire will not have to be forced. In small and medium-size boilers the rate of combustion should not exceed from five to seven pounds of coal per square foot of grate per hour. In larger boilers the rate of combustion of fuel mav be as hicrh as 202 GREENHOUSES from six to ten pounds per square foot per hour. A pound of best coal has a heating value of about 14,000 B. T. U. per pound, of which only about 60 per cent, or 8,400 B. T. U. are utilized in heating water or producing steam. It is the usual practice to estimate that each pound of coal will impart about 8,000 B. T. U. to the heating medium, and that each square foot of grate surface will burn about six pounds of coal per hour. This gives 48,000 B. T. U. per square foot of grate surface per hour. To find the approximate number of square feet of grate surface required to heat a given house, find the number of heat units re- quired, by the method described in Chapter XI, and divide by 48,000. In general, a square foot of grate surface is sufficient to supply 250 square feet of radiating surface. Fire Surface. — Fire surface (sometimes known as heating surface or water surface) is of two kinds; direct and indirect. The direct fire surface is that immediately above or around the fire, against which the light of the burning fuel shines. Indirect fire sur- face is that which receives the heat from the BOILERS, FUELS AND FLUES 203 burning gases on their way to the chimney. Direct fire surface is three times as effective as indirect. It does not follow, however, that boilers having the greatest amount of direct fire surface are the most efficient, for there must be sufficient length of fire travel- to consume the gases and enable them to give up the greater part of the heat of combus- tion to the water. To be most effective the fire surface is so arranged that the heat will impinge at right angles against it. This is accomplished with- out serious interference with the draft, and without making the course of the water in the boiler so long and tortuous as to in- terfere with its rapid circulation. The pro- portion of fire surface to grate surface dif- fers so widely in the different forms of boil- er construction that no definite rule can be given. It may vary from 15 to 35 square feet to each square foot of grate area. Types of Boilers. — Broadly speaking, there are three types of boilers, when classi- fied as to their form of construction : ( i ) Boil- ers in which the water is spread out in thin sheets between layers of iron or steel and against which the heat strikes; (2) tubular 204 GREENHOUSES boilers in which the burning gases travel through tubes or flues which are surrounded by water; and (3) water-tube boilers in which the water is contained in tubes about which the burning gases circulate. Many Fig. 103. — A type of ''vertical ' or "square" sectional boiler manufacturers combine two, and sometimes all, of the above types in one boiler. The two latter types are more commonly used for power purposes than is the first, but for heating establishments of moderate size a modification of the first is widely used. BOILERS, FUELS AND FLUES 205 Cast and Wrought-Iron Boilers. — The cast-iron boiler has a size limit above which it is impracticable to go, though two or more may be joined in a series. It is also claimed that on account of the thickness of the walls Fig. 104. — End view of "square" sectional boiler showing fire travel. A and B, push nipples for joining sections it is less economical of fuel than are wrought- iron boilers, which have thinner walls. On the other hand, cast-iron boilers do not rust as badly as wrought-iron ones when not in use, and they have no flues to be burned out by the sulphurous gases resulting from the 206 GREENHOUSES use of the poorer grades of coal. But they do sometimes crack, and they have a disgusting way of doing it at the most inopportune moment. Fig. 105. — Side view of "square" sectional boiler showing fire travel Where fuel is cheap and abundant, and especially in small ranges, or where the boiler is in a damp basement and likely to be neg- lected during the summer, cast-iron boilers are likely to give better satisfaction than wrought-iron. In large establishments of 100,000 feet or over, large wrought-iron tubu- BOILERS, FUELS AND FLUES 207 208 GREENHOUSES lar or water-tube boilers are almost always used. Styles of Cast-iron Boilers. — There are three general types or styles of cast-iron boilers. The most popular is the "vertical" or ''square"sectional boil- er. The advantages claimed for these forms of boilers are: (i) They may be enlarged by adding extra sec- tions; (2) a break or crack will usually be confined to one sec- tion; and (3) they may be made in large sizes because the individual castings are compara- tively small and light. The sections are joined together by accurate- ly ground push nip- ples or by screw nipples. Probably 80 per cent, of the cast-iron boilers now being placed in greenhouses of moderate size are of this general type- A second style of cast-iron boiler is known as "horizontal" or "round" sectional boiler. It gives good satisfaction in small Fig. 107.— A type of "round" or "horizontal" sectional boiler BOILERS, FUELS AND FLUES 209 ranges but is not made in large sizes. In a third style there are no sections, but the boiler proper is cast in one piece. For this reason its size is limited. It is also open to the disadvantage that a crack will spoil the whole boiler. It is little used at present. Fig. 108. — Corrugated fire box •boiler. The boiler proper is of a single casting Styles of Wrought-Iron Boilers. — Most wrought-iron boilers are either tubular or water-tube in construction, though the tubes or flues are sometimes connected with cast- iron headers. A new type of wrought-iron boiler is now being extensively advertised for greenhouse heating. It is claimed for this type that it steams more quickly than the 210 GREENHOUSES i'ig. 1U9. — Type of tubular boiler much used in green- house heating tubular boilers and that it is much more dur- able. As a rule users seem to be well satis- fied with it. Steam and Hot-water Boilers. — As usually constructed, low-pressure steam boilers dif- fer but little in construction from hot water boilers. The essential difference is that in steam boilers provision is made for a steam chest or storage above the water line, while in hot-water boilers the space between the top of the tubes and the top of the boiler is so small that there is no room for an adequate steam storage. This is equivalent to saying BOILERS, FUELS AND FLUES 211 Fig. 110. — Battery of two marine type boilers used for greenhouse heating that a steam boiler may be used for hot-water heating, but that a hot-water boiler is rare- ly satisfactory for steam heating. Large steam boilers are quite frequently used in hot-water heating when equipped with the necessary fittings which are described in a succeeding paragraph. Boilers for Soft and Hard Coal. — Hard coal burns with a ''short" flame, and much less fire travel is required to burn the gases than when soft coal, which burns with a ''long" flame, is used. More flue way is also re- quired for soft coal and the grates are more open. Most greenhouse boilers which are 212 GREENHOUSES designed for soft coal will burn hard coal equally well. If they are designed primarily for hard coal they will not burn soft coal efficiently. More grate surface is required for soft coal than for hard coal, because it is Fig. 111. — Wrought-iron boiler without flues more bulky weight for weight. Most mod- ern greenhouse boilers will burn either hard or soft coal, but a larger size will be required for soft coal than for anthracite. Boiler Ratings. — An approximate idea of the size of boiler needed may be found by figuring the amount of grate surface by the method described on page 202. Boiler manu- BOILERS, FUELS AND FLUES 213 facturers, however, rate their boilers show- ing their capacity. Some give the number of square feet of glass that they will heat to a given temperature; others give the number Fig. 112. — Sectional view of boiler shown in Fig. Ill of linear feet of radiating pipe of a given size which they will supply ; and still others, especially the manufacturers of large tubu- lar boilers, give the capacity of their boilers in terms of horse-power. Since different manufacturers often ques- tion the correctness of the ratings of their 214 GREENHOUSES competitors, it is but fair that buyers should be recommended to exercise consider- able caution. Probably most boilers will, under favorable conditions, develop the num- ber of heat units for which they are rated, but for the sake of safety and to prevent the necessity of forcing, it is best to select boil- ers with ratings at least 20 per cent, in ex- cess of the theoretical needs. When boilers are rated according to the number of linear feet of radiating pipe they will supply, it is usually given in terms of either 3%-inch cast-iron pipe or in 2-inch wrought-iron pipe. The following table gives the length of pipes of other sizes equiv- alent to I linear foot of 2 and 31/2-inch pipe. 1 ft. of 3-^4 in. C.I/ pipe equals.. 3.04 ft. 1 1 ft. of 3^ in. C.I. pipe equals.. 2.41 ft. VA 1 ft. of 3-^ in. C.I. pipe equals.. 2.10 ft. V/2 1 ft. of 3^ in. C.I. pipe equals.. 1.68 ft. 2 1 ft. of 3-^ in. C.r. pipe equals. .1.39 ft. 25^ 1 ft. of 2 in. W.I. pipe equahr. .1.806 ft. 1 1 ft. of 2 in. W.l. pipe equals. .1.431 ft. VA 1 ft. of 2 in. W.I. pipe equals. .1.25 ft. VA n. W.I. pipe n. W.I. pipe n. W.I. pipe n. W.I. pipe n. W.I. pipe n. W.I. pipe n. W.I. pipe n. W. I. pipe Most boiler ratings are given for a mini- mum outside temperature of zero degrees, Fahrenheit. For localities subject to a tem- perature of 10 degrees below zero a boiler of 10 per cent, greater capacity should be se- BOILERS, FUELS AND FLUES 215 cured, and for localities subject to a tem- perature of 20 degrees below zero, a boiler of 20 per cent, greater capacity should be se- cured. The term horse-power, as applied to boil- ers, represents the energy developed in evap- orating 34.5 pounds of water per hour from a. temperature of 212 degrees, or the develop- ment of 33,317 B. T. U. per hour. Roughly, a heating boiler will supply 100 square feet of radiation for each horse-power which it develops. Fig. 113. — Altitude giiage for hot water boiler Boiler Accessories. — It has already been stated that a steam boiler may be used for hot-water heating by simply changing the fittings. When used for hot-water heating 216 GREENHOUSES the boiler is fitted with an altitude gauge, which shows the height of the water in the system; also with a thermometer to show the temperature of the water. A valve is pro- vided for draining the boiler and, if desired, an automatic damper regulating device may be installed. When used for steam heating the boiler is only partially filled with water, and a water column and guage is necessary to indi- cate the height of the water. A steam guage is also necessary to indicate the pressure; and a safety valve to automatically re- lieve the pressure, if it be- comes too great for safety. Steam boilers are usually Fig. 114.— Water col- .... ^ 7 umn and guage for equipped With automatic steam boilers hamper regulators. They are rather more efiicient than the regulators used on hot-water boilers. A drainage valve is provided the same as for hot-water boil- ers. Many states require that all steam boil- ers be equipped with a fusible plug, which is simply a brass plug with a tin core, which BOILERS, FUELS AND FLUES 217 Fig. 115. — Steam guage is screwed into a hole in the boiler near the bottom. If the water level falls below the plug the heat melts it out, thus making Fig. 116. — Diagram of automatic damper regulator. The steam pressure acts against a flexible diaphram which is connected with the dampers by means of a lever and chain 218 GREENHOUSES an opening and lessening the danger of an explosion. The boiler and all pipes, except those in the greenhouse itself, should be insulated as much as possible to prevent loss of heat. The best known material for this purpose is as- bestos. For coating boilers it may be had in a granular form, which is mixed with water and applied with a trowel or the bare hands. For covering pipes molded casings may be had to fit all sizes of pipe. Fig. 117. — Asbestos pipe covering FUELS Coal is used almost universally for fuel in greenhouse heating, except in sections where natural gas or oil are cheap and abundant. Gas is an ideal fuel, but somewhat treach- erous inasmuch as the pressure is likely to be lowest in the coldest weather. Care should be taken to see that there are no leaks, as it is very explosive, and it is also poisonous to vegetable as well as animal life. Broadly speaking, coal is of two kinds, BOILERS, FUELS AND FLUES 219 anthracite or hard coal, and bituminous or soft coal. Hard coal burns with little smoke Fig. 118. — Boiler etiuipped for using natural gas and IS much heavier than soft coal, although it may not develop as much heat per ton. 220 GREENHOUSES It is easier and cleaner to handle, and re- quires less attention in firing, but in most sections is more expensive. Soft coals are of two general types; The free burning and the coking. The latter fuses together in burning and is somewhat more difiicult to handle in the furnace than the free burning, though it is preferred by some firemen. The heating value of a coal depends upon the percentage of total combustible matter contained, and upon the heating value per pound of the combustible portion. In some semi-bituminous coals the heating value runs as high as 15,750 B. T. U. per pound. The heating value of a few common types of coals as given by Kent are shown in the fol- lowing table. Kind of coal B.T.U. Kind of coal B.T.U. Anthracite Cambria Co., Pa. . . . 14450 Northern Coal field ..13160 Somerset Co., Pa. ...14200 East Middle field ...13420 Cumberland, Md 14400 W^est Middle field ...12840 Pocahontas, Va 15070 Southern field 13220 Brier Hill, 0 13010 Scott Co., Tenn 13700 Semi-'bituminous Big Muddy, 111 12420 Clearfield Co., Pa. ...14950 Missouri 12230 Soft coal is more commonly used in green- houses than is hard coal. This js especially BOILERS, FUELS AND FLUES 221 true in large establishments. The price varies with the quality, distance from the mines, etc. The average cost for soft coal to 6i grow- ers, living east of the Mississippi River, for the season of 1911-12, was $2.33 per ton. The average amount used for the season was 11.6 tons for each 1,000 square feet under glass. Underfed Boilers. — The term "underfed" is applied to a method of stoking, in which the coal is fed from the bottom instead of the top of the furnace. It is claimed for this system that it insures a more perfect combustion and that cheaper grades of coal may be used. Boilers employing this prin- ciple have not come into very general use in greenhouse heating, probably because they will not handle successfully all grades of coal. Self-stoking Boilers. — Stoking devices are practical only in large establishments us- ing large boilers. There are several types, some of which work on practically the same principle as the underfed furnaces mentioned above, except that their action is automatic. In other forms the grate bars are arranged in the form of an endless chain, which is 222 GREENHOUSES moved slowly from the front to the rear of the fire-box by means of gearing. It is claimed for the self-stoking devices that they not only save labor, but that they are more economical in the use of fuel than is hand stoking. Points to Consider. — The following points should be kept in mind in selecting a green- house heating boiler: 1. It should be of ample size — at least one size larger than is theoretically necessary. 2. The fire-box should be deep and spac- ious. This is especially true of boilers for small establishments where a regular fire- man is not employed. 3. The combustion chamber (the chamber above the grate) should be large enough to insure thorough combustion of the gases. 4. The boiler should be so arranged that it may be easily cleaned, especially the flues and heating surfaces. 5. The grates should be heavy but easy to operate and easily removable, so that re- pairs may be made quickly. 6. The water travel should not be so cir- cuitous as to prevent of rapid circulation. 7. There should be no packed joints. All BOILERS, FUELS AND FLUES 223 unions should be made with push or screw nipples. 8. Soft coal burners require a somewhat different construction than do hard coal burn- ers. The kind of fuel to be burned should be clearly in mind when selecting a boiler. 9. The ash pit should be deep and com- modious. Shallow ash pits are likely to be- come filled so that the draft is impaired and the grate bars ruined. CHIMNEYS AND FLUES A very essential part. of the heating equip- ment is the chimney or flue. Its purpose is twofold: First, to create a draft in order to furnish air to promote combustion; and second, to carry off smoke and gas. The size and height of the chimney required de- pends on the size of the grate surface. Mere velocity does not- necessarily indicate that the draft is sufficient; the chimney must be of sufficient size to carry the required quantity. The velocity of the gas in the flue depends on the height of the flue and upon the tem- perature of the gas. The difference be- tween the weight of the hot gases in the chimney, and a column of cold air of equal 224 GREENHOUSES size outside creates a flow upward in the chimney. This difference increases with the height of the chimney, and if the difference in temperature increases the velocity is more rapid. Locations high above sea level require higher chimneys than those near sea level, on account of the rarety of the atmo- Fig. 119. — Chimneys should extend above the roofs of adjacent buildings Sphere. For example, at Denver, Col., (5,300 feet) the height should be about 20 per cent, greater than at sea level. Chimneys should be vertical if possible and the inside should be smooth and free from all obstructions. They should also extend well above the roofs of adjacent buildings, particu- larly when there is danger of a "down draft." Round chimneys present less sur- face per cubic capacity than do square chim- neys, and are thus more efficient. For the same reason square flues are better than ob- long flues. BOILERS, FUELS AND FLUES 225 The following table shows the size and height of chimneys required by steam boil- ers. For hot-water boilers multiply the radi- ating surface by 1.5. Height of chimney in feet Sq.ft. f 20 30 40 50 60 80 100 120 st'm rad Size of Chimney (dia. or 1 sid e sq.) in inch es 250 7.4 7.0 6.7 6.4 6.2 6.0 6.0 6.0 500 9.6 9.2 8.8 8.2 8.0 6.6 7.3 7.0 750 11.3 10.8 10.2 9.6 9.3 8.8 8.5 8.2 1000 12.8 12.0 11.4 10.8 10.5 10.0 9.5 9.2 1500 15.2 14.4 13.4 12.8 12.4 11.5 11.2 10.8 2000 17.2 16.8 15.2 14.5 14.0 13.2 12.6 12.1 3000 20.6 18.5 18.2 17.2 16.2 15.8 15.8 14.4 4000 23.6 22.2 20.8 19.6 19.0 17.8 17.0 16.3 5000 26.0 24.6 23.0 21.6 21.0 19.4 18.6 18.0 6000 28.4 26.8 25.0 23.4 22.8 21.2 20.2 19.5 7000 30.4 28.8 27.0 25.5 24.4 23.0 21.6 20.8 8O0O 32.4 30.6 28.6 26.8 26.0 24.2 23.4 22.2 9000 34.0 32.4 30.4 28.4 27.4 2S.6 24.4 23.4 10000 27.0 34.0 32.0 34.0 28.6 27.0 25.4 24.6 15000 ■ • • • • . 38.4 36.2 35.0 33.0 31.0 29.2 20000 • • • 43.0 42.0 41.0 37.0 35.0 34.0 30000 .. .. . .. . 50.0 48.0 46:0 43.0 41.0 CHAPTER XIV WATER SUPPLY AND IRRIGATION An abundant supply of water at a reason- able cost is necessary for the successful op- eration of a commercial range of green- houses. Figures compiled from the experi- ence of several growers show that the con- sumption of water by a vegetable crop in a greenhouse during the bright, hot days of June and July may be as high as 280 gallons per day per 1000 square feet of crops. As the watering is done over a period of not more than three or four hours per day, it is necessary to make arrangements to supply the maximum amount needed during that length of .time, rather than during the 24 hours of the day as is usually figured for domestic purposes. When city water is available at a reason- able price it is doubtful if it will pay the small grower to go to the expense of pro- viding a private supply. Sometimes, how- ever, the conditions are such that a private 226 IRRIGATION 227 supply of water may be had at small expense from springs, ponds or streams. In larger establishments it may be cheaper to install a private system than to depend on city water. Often, also, the ranges ar^ located out- side the city limits where city water can- not be had. Data based on the reports of nearly lOO florists and vegetable growers show that the average cost per I, GOO gallons of city water is i8 cents, and that the average cost of the home supply, includ- ing cost of equipment, depreciation and main- tenance, is 21 cents per I, GOO gallons. Pumps. — For gen- eral purposes some of the many types of combination lift and force pumps now on the market are com- monly used. Pumps of this type may be had which are directly geared to a gas or steam engine, or to an Fig. 120. — Pumping- jack for applying power to a hand pump 228 GREENHOUSES MANHOLE ^5 I I S ^ ^ COMPHESS^D AIR electric motor. Usually, a hand pump of large size is used, and power is applied by means of a pumping jack. A very efficient but somewhat delicate pumping device is the combined hot-air- engine and pump. These pumps give very good satisfac- tion where the water is reasonably close to the surface, or when it does not have to be pumped against too great a pressure. Improved types of large size are now available, and are verv econ- omical of fuel, but the engine is not as well adapted for general power pur- poses as are gas en- gines. A form of pump, which is becoming quite popular for domestic use is the auto-pneu- matic pump. It is designed to be used in an open well or a cased well of large bore, as the pump proper is placed entirely be- kYSlL CAS f A/ a ZOW ir/Ar£ff i£ysi. IA/C/f£AS£.'7 3/4f"^/^£ ■AUTO -fN£aMAT/e Fig. 121. — Diagram showing installation of an auto- pneumatic pump IRRIGATION 229 neath the water. It is operated by com- pressed air, hence an air pump and an air tank are required. Its chief advantage for domestic purposes lies in the fact that it starts automatically when the faucet is opened, thus giving a supply of cold water direct fr.om the well. For greenhouse pur- poses this is a disadvantage, as the water may be too cold to use on the plants. Pump cylinders should not be more than 20 feet above the surface of the water, as this is the limit of practical suction. When the water is more than 20 feet below the surface the pumping cylinders are lowered accord- ingly. In deep wells it is common to lower the pumping cylinders well into the water. Capacity of Pumps. — The capacity of a pump depends upon the size of the cylinder and the length and rapidity of the strokes. The table on page 230 gives the discharge per stroke in gallons, of pumps having cylinders of various sizes. This, multiplied by the number of strokes per minute, will give the capacity per minute. Power Required. — The power required to operate a given pump may be determined as follows: Multiply the number of gallons pumped per minute by 8.337 pounds (the 230 GREENHOUSES 00 0 ON 0 0 eg 0 vo 00 V5 1— ( T— < Th 00 vo f^ 0 vo Tf to j On q Tt; r^ '— ' y—t T— ( m w C^ fO 10 t^ On CO VO 0 -+ On Cli 4; »— ( ^ vo 10 vo CO ? LO vq CO g CO eg ^. 1^ "rt ^ T— ( 1— I p bo PL| _c 0 * vo CO VO t^ rt- On 0 On Th fe '■^ v-H CO »— ( 0 T— ( ■^ 00 U-) eg eg a> a; »— ( CNl CO Tt 10 vq 00 q eg o 0 0 1—1 1— ( > 4-> to ■J-J cn W) -< cq o\ t>. t^ On »— ( vo eg 0 U 0 1— ( »— ( C^ CO ^ vq tNj On 1—1 < ^ D, 1— t Ph 4-1 bo c >^ < ■♦-» On 0 to CO 10 1— 1 0 CO o\ u 00 u 0 r^ ^ CO CO 10 00 eg 1^ 4J 03 T— ( »— 1 OJ CO rt 10 vq 00 On fe I-] ' o U w LO On Tj- (M T— 1 eg 10 0 t^ t>^ S. ^ y—t On 00 00 On eg to J r— I » 00 PQ < H J_ C/5 SIN \(N \(V) \(N -<-' (D ID M\ H-\ v-\ ^ 2:J-o^ rgegcocoTfTttotoNo £ C JrJ Q C^ IRRIGATION 231 weight of a gallon of water). This will give the weight pumped per minute. Multiply this by the total lift in feet. This will give the number of foot-pounds of energy required per minute. Divide this by 33,000 (the num- ber of foot-pounds in a horse-power) and the result will be the number, of horse-power re- quired. Pumping outfits are only about 50 per cent, efficient, so that the results ob- tained by the above are doubled in actual practice. On the average one horse-power will pump 30 gallons per minute to the height of 100 feet. In pumping water against press- ure in a pneumatic tank, extra power will be required. Extra power will also be re- quired when the waten is pumped for any considerable distance, on account of the fric- tion of the pipes. The frictional loss in feet of lift for each 100 feet of pipe of various sizes is shown in the following table. allons Size of Pipe ;r min. ^ in. lin. P4in. 13^ in. 2 in. 2V2 ir Frictional Loss 10 29.9 1.Z 1.4 1.0 0.28 0.09 15 66.0 16.1 5.5 2.2 0.57 0.18 20 115.0 28.0 9.5 4.8 0.96 032 25 179.0 43.7 14.7 6.0 1.7 0.48 30 264.0 63.2 21.0 8.6 2.1 0.69 35 372.0 85.1 28.9 11.6 2.7 0.92 40 461.0 110.0 37.0 14.9 Z.l 1.2 232 GREENHOUSES This loss by friction cannot be disregarded. Suppose, for example, it is desired to deliver 20 gallons per minute at a distance of 100 feet. By referring to the above table it will be seen that if a ^4-inch pipe were used, a loss equal to a head of 115 feet would be sustained, while if a iy2-inch pipe were used a loss of only 4.8 feet would be sustained. It is economy to use pipe of generous size. Hydraulic Rams. — The hydraulic ram is a device which utilizes the force of water. Fig. 122. — A simple type of hydraulic ram. a, intake pipe; f, delivery pipe IRRIGATION 233 falling a short distance, to elevate a portion of the water to a greater height. It is wasteful of water, but when a never-failing stream of sufficient flow and fall is avail- able it is one of the most economical and satisfactory of water-lifting machines. Rams are somewhat difficult to install by a novice, because of the rather exacting con- '"^^ rtfw*r/o« ^etr k Livim cMri vNtvft Fig. 123. — Plan for installing a hydraulic ram ditions necessary to secure the most efficient service. When they are properly installed, however, they give little trouble, provided they are kept from freezing. Capacity of Rams. — To find the capacity of a ram for any given conditions proceed as follows : Multiply the fall in feet by the quan- tity of v/ater which may be supplied to the ram in gallons per minute, and divide the product by the height the water is to be raised. The result will be the number of gallons delivered per minute. The above 234 GREENHOUSES disregards loss by friction and assumes that a ram of the proper size is installed. By use of the table on page 235 an estimate of the capacity of a ram for different con- ditions may be determined. The left-hand column indicates the number of feet of fall possible to secure, and the numbers at the top of the vertical columns indicate the height to which water is to be raised. For example: Suppose we have a stream with a flow of 100 gallons per minute; that there is an available fall of 10 feet, and that it is desired to raise the water 40 feet. The factor in this case (252) will be found in the column headed by 40 and opposite the num- ber 10 under power head. Multiplying 252 by 100, we have 25,200, the number of gal- lons that may be delivered per day by a ram of the correct size. In ordering a hydraulic ram the following information should be given: 1. Flow of water in gallons per minute. 2. Vertical fall in feet. 3. Distance in which fall is obtained. 4. Vertical height above ram the water is to be raised. 5. Distance water is to be forced. 6. Number of gallons required per day. IRRIGATION 23.J JZ; -^ fOrhiOVOvOt^COO'— ((M-rl-iOvooOOO Q f^ orO'^voooO'too<»^0'^cocoThi/-) o o r^VO OOC\i-HC-l^voONCgiOOrot^Or^O'^ I— I ??C5 vo>j^Tj-TfcorJZ 4 2 8 478 4 2 10 598 4 2/ 8 598 4 2/2 10 748 4 3 8 718 IRRIGATION 239 o o U b£ a; ':c 240 GREENHOUSES IRRIGATION There are two general methods of water- ing greenhouse crops aside from hand water- ing. One is by an overhead sprinkling sys- tem; the other is by an underground or sub- irrigating system. Of these the overhead system is by far the more popu- lar. A census of a large number of growers of greenhouse vege- tables shows that practically 75 per cent, use some form of over- head irrigation, while only two out of the whole number con- sulted were using sub-irrigation. Practically the only system of overhead irrigation used in greenhouses is one in which pipes, fitted with nozzles which Fig. 125 — A throw a rain-like spray, are run type of nozzle . ,. . r ^i t j used in over- lengthwise of the house and so head irrigation arranged that they may be rotat- ed to throw the spray on both sides of the pipe line. The original system is known as the Skinner system, but there are others now on the market. Pipe lines for this system should be about 16 feet apart and as far from the foliage as possible. The nozzles should be 3 feet apart. This system will operate IRRIGATION 241 satisfactorily on a' water pressure of from 10 to 30 pounds. When constructing benches for sub-irriga- -A Fig. 126. — Greenhouse bench arranged for sub-irrigation. A, cement troughs on bottom of bench; B, drain tile or perforated pipes for supplying water; C, drainage spaces between troughs. tion, the essentials are a water-tight bottom, usually of cement, to prevent the water from leaking through, and perforated pipes or tiles for distributing it along the bench. This system has been tried out extensively with varying results by the Ohio experiment station. CHAPTER XV CONCRETE CONSTRUCTION Concrete is a combination of Portland cement, sand, crushed stone or gravel and water, thoroughly mixed and then allowed to set or harden. Portland cement, or cement, as it is now commonly known, is manufactured by burn- ing and grinding together limestone and clay, or shale, in certain proportions. It de- rives its name, Portland cement, from its re- semblance to Portland stone. It is also sometimes known as hydraulic cement, or building cement. Concrete has wellnigh revolutionized building practice in the last 25 years, but in no case has it displaced masonry to a greater extent than in greenhouse construction. Formerly, the walls of a greenhouse were a source of much trouble, because of their rapid deterioration, but it was soon found that when conc'rete was used they be- 242 CONCRETE CONSTRUCTION 243 came the most stable part of the structure. Concrete is practically the only material now used for the foundations and walls of com- mercial greenhouses, and to a g^reat extent it has displaced masonry for private greenhouses. At present cement is almost universally handled and shipped in cloth or paper sacks holding 95 pounds. It is often spoken of, and is sometimes quoted by the barrel, 'this now meaning simply four sacks, or 380 pounds. As a rule, the most satisfactory form in which to buy cement is in cloth sacks. The sacks may be returned when empty, and if not torn a credit of about 10 cents each may, be realized. Sand. — Sand, to give the most satisfac- tory results, should be free from clay or or- ganic matter, and rather coarse. \^ery fine sand will require a greater proportion of cement and aa a consequence the concrete will be more expensive. In a small way, sand that contains some organic material may be washed and thus made satisfactory-, but it is an expensive process. 24.4: GREENHOUSES Stone. — Either crushed stone or gravel may be used in making concrete, the only difference being that the crushed stone usual- ly has a cleaner surface and the cement will cling to it more tightly. When gravel is used it should be free from clay, and the in- dividual stones should be clean and bright and not covered with a layer of clay or soil. The size of the stones may range from a fourth to two and a half inches in diameter, the size depending on the use to which the concrete is put. The best results are ob- tained when the sizes vary regularly from small to large, in order that they may settle well together when the concrete is poured. Run of the Bank gravel is sometimes used. This is economical only when it contains sand and gravel in the correct proportions, as explained in a succeeding paragraph. Crushed Stone may also contain very fine, medium and coarse stone in the correct pro- portions, so that no sand need be added, but such a condition is rare, unless tlie stone is ground and furnished for this special pur- pose. CONCRETE CONSTRUCTION 245 Proportions of Materials. — Theoretically, the ideal concrete is a mixture in which all the spaces between the stones or gravel are C£M£NT «?7-d?/r2r COA/C/?£T£ Fig. 127. — Proportions of cement, sand and stone re- quired to form concrete filled with sand, and all the spaces between the grains of sand are filled with cement. From this it will be seen that the total bulk of concrete would not be greatly in excess of the bulk of stone or gravel, as the sand and cement would go to fill the vacant spaces (voids). This is really true except that, as usually proportioned, a slight excess of ce- ment is allowed. This is wise in order to insure that there shall be a film of cement about each stone and grain of sand, so they may be all bound together in a solid mass. The common formula for most concrete work is known as the i :2 14 mixture. In this there are: i part by measure of cement, 2 parts of sand, and 4 parts of stone or gravel. 246 GREENHOUSES This is the formula commonly used for walls above ground and for bridges and similar work. For sidewalks, floors, etc., which are supported on a firm foundation and are not subjected to heavy strain, a weaker mixture of T part of cement, 2M parts of sand and 5 parts of stone or gravel, is sometimes used. For plastering the outside of walls and for similar purposes a mixture of cement and sand alone in the proportion of i to i is used, as it is easily worked and leaves a smooth surface. Mixing. — For small jobs concrete is usually mixed by hand. The essentials are: (i) A tight platform or mixing board of suf- ficient size; (2) a convenient measuring box; (3) suitable shovels; and (4) a supply of water. Quite commonly the sand and gravel is measured in the wheelbarrows in which it is hauled, a little experience, secured by carefully measuring the amount for a few times, being all that is necessary to insure sufficiently accurate measuring. The bar- row loads are checked up from time to time, however, to see that they are not over-run- ning or falling short. CONCRETE CONSTRUCTION 247 It is convenient to mix in batches requir- ing even bags of cement. For example, a two bag batch would mean two bags of ce- ment, a quantity of sand equal to 4 bags (3^ cubic feet) and 8 bags (7/4 cubic feet) of stone or gravel. They are mixed together thoroughly, shoveling over several times be- fore adding the water. Amount of Water. — The quantity of water used has but little effect on the resulting con- crete, the amount depending rather on the consistency at which the concrete can best be handled for the special purpose for which it is to be used. The dryer the mixture the more quickly it will set. For thin walls, or where the form con- tains many indentations, the mixture should be thin enough to run off the shovel cfuickly in handling. For, walls of medium thickness (6 to 12 inches) or for floors, walks, etc., it should be jelly-like in consistency, so that it will ])ile up somewhat on the shovel, but will slowly settle and run off the sides. For foundations, underground, where it is important that the mixture set as quickly as 248 GREENHOUSES possible, it may be mixed so dry that it will handle like damp earth. Care must be taken in making this "dry mixture" that every part is moistened. Estimating Materials. — The quantity of cement, sand and gravel necessary for a giv- en piece of work may be found by multiply- ing the number of cubic feet by the percent- age of cement, sand and gravel in a cubic foot of the mixture to be used. For con- venience these proportions are given in tabu- lar form in terms of barrels of cement and cubic yards of sand and gravel. TABLE SHOWING PROPORTIONATE QUANTI- TIES OF CEMENT, SAND AND GRAVEL IN A CUBIC FOOT OF CONCRETE Cement Sand Stone or gravel Mixture barrel cubic yard cubic yard 1:2 :4 0.058 0.0163 0.0326 1:2>4:5 0.048 0.0176 0.0352 To use, multiply the number of cubic feet of concrete required by the factor shown in the table. The result will be the quantity of the material required. For example, looo cubic feet of 1 12:4 con- crete would require CONCRETE CONSTRUCTION 249 1000 X 0.058 or 58 barrels of cement 1000 X 0.163 or 16.3 cubic yards sand 1000 X 0.0326 or 32.6 cubic yards gravel In estimating for cement mortar, figure i cubic foot to each 15 square feet of surface to be covered. Each cubic foot of i :i sand and cement mortar requires 0.1856 barrels of ce- ment and 0.0263 cubic yards of sand. Forms. — As concrete is soft when mixed, it is necessary to have some kind of a form or mold to hold it in the desired form and position until it hardens. For foundations, for such structures as greenhouses, a trench is usually dug 12 or 14 inches wide, and deep enough so that the bottom will be below the frost line. If the soil is firm enough to hold its place no form will be needed, but the concrete may be poured directly into the excavation, tamped and allowed to harden. For that part of the wall which is above ground, however, a form is needed. It is important that this form be vertical, that it be straight, and that it be smooth in tlie inside so that the resulting wall will be agree- able to the eye. The making of the forms is important. They should be built by an ex- perienced carpenter. 250 GREENHOUSES Any kind of lumber which is free from knot holes and has been surfaced to an even thickness will answer for forms. If the wall is a high one it may be necessary to tie the sides of the form together with wire. The wires remain in the concrete when the form is removed, but may be cut off flush with the surface, and if the wall is plastered they will not be noticed. Fig. 128. — Form for a concrete wall CONCRETE CONSTRUCTION 251 Filling the Forms. — In filling the form the concrete is placed in layers about 6 inches deep and tamped lightly until water shows on the surface. This will insure its settling together closely- If the wall is not to be plastered and a smooth surface is required, a spade or paddle is run down all along between the concrete and the sides of the form when the concrete is poured. This will force the larger stones toward the center of the wall and allow the smaller stones and sand to fill in next to the form, thus I'l /A 'M k-mm ■:^]:Ma Fig. 129.— Meth- od of facing a concrete twall making a smooth surface. Reinforcing. — Concrete will withstand enormous crushing loads, but in walls where there is a considerable side strain, it should be reinforced with iron or steel. The best materials for this purpose are iron or steel rods. If they are twisted or roughened in some manner, so that the concrete will ad- here to them tightly, their efficiency will be greatly increased. They are put in the 253 GREENHOUSES forms, usually vertically, about midway be- tween the sides and 2 or 3 feet apart before the concrete is poured. When an extra strong wall is required rods may be laid horizontally on the top of every layer or every second layer as the concrete is placed and tamped down into the soft mix- ture. When the walls extend only 3 or 4 feet above the surface and are at least 8 inches thick as is commonly the case in greenhouses, little if any reinforcement is needed. Walks and Floors. — Concrete walks are now very commonly used in commercial as well as private greenhouses, and the boiler and service rooms are usually floored with concrete. As the walks are not usually sub- ject to as hard usage as those laid out-of- doors, or to the action of frosts, it is not necessary to make them quite as thick, but in other respects they differ but little from the concrete sidewalks now so common. The common method of building walks in a greenhouse is to make an excavation a few inches deep and as wide as the walk is to be and fill it with broken stone, pieces of brick, etc., to make a foundation. On top of this, two pieces of straight 2 x 4-inch lumber are placed on edge, level with each other and CONCRETE CONSTRUCTION 253 with their inside edges spaced just as far apart as the walk is to be wide. They are then fastened by driving stakes on the out- side and naihng. The concrete is then poured into this form to within about an inch of the top and tamped firmly. A top coat, usually of finer material, is then placed on top of the first layer before it is set, and struck off by running a straight edge along C- Fig. 130. — Structure of a concrete walk, a, foundation; lb, coarse concrete; c, finish coat of fine concrete the tops of the side pieces. This is then troweled by hand to give a smooth and slightly curving surface. To allow for expansion and contraction, the walk should be cut into blocks before it sets. This may be done by putting in pieces of thin sheet-iron at regular intervals to be removed when the concrete has partially hardened. Sometimes the walk is cut through with a spade while still soft, at regu- lar intervals and fine, dry sand placed be- tween the blocks so made. Tliis is usually quite satisfactory and by careful troweling 254 GREENHOUSES a very neat walk may be made in this way. For the lower layer, when there is a firm foundation, a i :2>^ 15 mixture will be satis- factory. The top layer should be of a 1:2 4 mixture or, when an especially smooth sur- face is required, of a 1:2 mixture, that is, one part of cement and two parts of sand. Floors are laid -practically the same as walks, except that they are usually troweled level instead of curving. The work is begun at one side of the floor, and as soon as one section has been laid and has had time to set, the side boards are taken up and put down for the next section. Floors should seldom or never be laid in a solid mass. Waterproofing. — Much trouble is often experienced in underground boiler rooms from water. The- best protection is to lay a row of tile completely around the outside of the foundation, at the bottom, and connect it with the sewer or drain. If the bottom of the cellar is springy it may be necessary to lay the floor in a solid piece and in two layers. After the first layer has set and become dry, or nearly so, a thick coating of hot tar may be applied, allowing it to ex- tend for a few inches up the side walls. When this has hardened put on another coat CONCRETE CONSTRUCTION 25o of rich concrete, troweling it up the sides as far as the tar has been placed. When an absolutely watertight job is required it may be necessary to coat the entire outside sur- face of the walls with tar and then bank up with earth. Several so-called waterproofing materials designed to be placed in the concrete when Fig. 131. — A small power machine for mixing concrete it is mixed are on the market, but as, a rule they are not fully satisfactor}^ Concrete Blocks. — Blocks made of con- crete in special molds or forms are sometimes employed for walls. They are usually hol- low and for that reason make a warmer and somewhat dryer wall than does solid, poured 256 GREENHOUSES concrete. Experience shows that as a rule they are less durable than solid walls, but when the cost of material and labor for mak- ing forms is considered they may be more economical. They are often made with an ornamental face resembling broken stone, and make a somewhat more pleasing appear- ance than a plain wall. Cost of Concrete. — So many factors enter into the cost of concrete that no reliable general estimate can be given. The price of cement is now fairly constant and uniform. The cost of sand and gravel or crushed stone, on the other hand, differs widely. In some places it may be had on the premises, in others it may have to be transported for several miles. Other factors entering into the cost are labor and the size of the opera- tion. Where the quantity of work will justi- fy the use of a power mixing machine, the cost is usually less than when the mixing is done by expensive hand labor, although the cost for labor may often be greatly reduced by carefully planning the work. In general the contract prices for walls on comparatively small jobs range from 7 to 20 cents per cubic foot, and for walks and floors from 4 to 15 cents per square foot. CHAPTER XVI PLANS AND ESTIMATES The cost of any kind of a building must necessarily vary with the cost of building material and the price of labor. This is es- pecially true with greenhouses, since the ma- terials used (glass especially) are subject to extreme fluctuations in price. In the pre- ceding chapters it has been the aim to give all the data necessary for estimating the amount of material required for any given house, but no attempt has been made to state definite prices. Little can be added in this chapter to what has already been given, and it would be use- less repetition to collect the data into one chapter, as it may be easily found by refer- ring to the index. An efifort has been made, however, to make some suggestions as to the probable cost of difTerent types of houses un- der varying conditions. Basis of Estimates. — Since the economic value of a greenhouse depends on the area of 257 258 GREENHOUSES surface covered (bench space) it is common to estimate costs in terms of square feet of surface covered. In an investigation among a large number of growers (all types of houses) the author found that the first cost averaged not far from 45 cents per square foot of surface under glass. This included cost of heating system, but did not include cost of service buildings. The cheapest plant on which data was se- cured was a range of four all wood frame houses, 16 X 50 feet, which had been in serv- ice for nine years and which was built at a cost of $525, or about 22 cents per square foot. In this case a second-hand boiler was used. Several larger ranges heated by steam from a central heating plant have been built at a cost of between 30 and 40 cents per square foot, though at a time when material was low in price. Data on modern semi- iron construction, when the labor was per- formed for the most part by the owner and his help, show a cost of between 50 and 60 cents per square foot, and all iron construc- tion between 60 and 75 cents per square foot. All these, of course, were standard commer- cial houses. Private and public conserva- PLANS AND ESTIMATES 259 tories and ornamental houses often cost two and three times as much. Detailed Estimates. — Detailed estimates necessarily differ with the grade of material used. The following is a detailed estimate at current prices of the material needed for and the cost of a sem-iron frame house 30 X 90 feet, not including labor of erecting. 850 cubic feet concrete ('wall and piers) — 50 barrels cement 14 cubic yards sand 28 cubic yards gravel $100 PIPE Side Posts — 32 pieces 2-inch pipe, 5 feet 6 inches Purlins — • 360 feet V4 inch Purlin Supports — 24 pieces 1^-inch pipe, 8 feet 3 inches 24 pieces l>4-inch pipe, 11 feet Cross Ties — 24 pieces 1^-inch pipe, 5 feet 24 pieces T^-inch pipe, 8 feet 6 inches Pipe and fittings for water lines, 100 feet ^4 inches $75 PIPE FITTINGS 32 Gutter brackets 120 Clamp fittings 48 Foot pieces 140 Purlin clasps $30 MILL WXDRK 240 feet sill 180 feet eave plate 260 GREENHOUSES 90 feet ridge 180 feet drip gutter 4 pieces gable rafter, 18 feet long 268 pieces sash bars, 18 feet long 4 pieces corner bars, 4 feet long 268 pieces glazing bars, 4 feet long 180 feet sash header 330 feet glazing bar 100 feet 2x4 for door casing and gable bracing 1 door Ventilator sash with stops $200 GLAZING 86 boxes glass (16x24) 500 pounds putty 8000 glazing points $250 Ventilating apparatus $25 Nails and other hardware $25 Paint $50 Freight $15 Miscellaneous items $25 HEATING Boiler (hot water) Pipe and fittings Brick for flue $550 Total $1345 This house covers approximately 2700 square feet of surface, which at a cost of $1,345 gives a cost per square foot of 49.81 cents for materials, but not including labor. Figures on a similar house 31 x 100 feet submitted by a well-known manufacturer of greenhouse materials are given below: PLANS AND ESTIMATES 261 WOODWORK 200 feet gutter with drip 100 feet ridge 228 feet glass sill 175 feet gable end bars 4 pieces gable rafters, 18 feet long 144 pieces sash bars, 18 feet long 12 ventilators 12 pieces ventilator sash cap 60 headers 144 side bars 4 corner bars 1 door $177.01 Ventilating machine complete $26.40 Hinges for ventilators 3.60 Trussing material 5.20 Hardware for doors .63 PIPE, POSTS AND FITTINGS (walls) 40 pieces 2-inch, 5 feet long 40 pieces post tops $27.20 Nails 2.50 10 pounds glazing paints 1.30 400 pounds putty 14.00 Paint 32.00 Glass, 4600 square feet 260.00 Purlins, fittings and purlin supports 61.75 Gable bracing material 2.50 Heating plant complete 703.33 Total $1317.42 The latter estimate does not include cost of materials for walls, but in other ways is complete. The cost per square foot of sur- face covered is 43.9 cents not including wall and cost of erection. 262 GREENHOUSES For an all wood frame house the cost of material will probably be from 15 to 25 per cent, less than the above and ♦the cost of erection from 10 to 20 per cent. less. For an all metal frame house the cost for materials will range from 25 to 40 per cent. greater than for the semi-iron construction, but the cost of erection will be less. Information Required for Estimates. — In writing for estimates the following informa- tion should be given : 1. Type of house (semi-iron, all metal, etc.). 2. Kind of roof (even span, three quarter span, etc.). 3. Length and width (if range, send sketch showing arrangement). 4. Height to eaves. 5. Pitch of roof or height to ridge. 6. Size of glass preferred. 7. Kind of heat (hot water, steam, vapor). 8. Temperature to be maintained. 9. Coldest outside temperature expected. 10. Kind of fuel (hard or soft coal). INDEX A PAGE All-metal frame greenhouses 91 Asbestos covering for furnaces and pipes . . 218 B Beds (greenhouse) ...... 143 curbs for 156 of hollow building tile 145 Benches .... 143 arrangement of 153 concrete 149 for sub-irrigation 241 height and width of 152 iron frame 148 wood .... 146 Boilers .... 20O accessories for 215 arrangement for steam heati ig 197 cast iron 205 essentials of . 201 hot water 210 for hard and soft coal . 211 ratings of ... . 212 self stoking 221 steam .... 210 styles of cast iron 208 styles of wrought iron . 209 types of . 203 under-fed 221 wrought iron 205 C Cast iron boilers .....•• 208 Chimneys and flues ...... 223 size and height of . . . • • • 225 Coal cost of 221 heating value of . . • • • • ??? kinds of . . . iJiy 263 264 INDEX Coils (heating) arrangement of length of for hot water heati length of for steam heating Coldframes described construction of Cold-pits Concentric system of framing Concrete construction blocks cost of estimating material filling forms forms for mixing water needed for water proofing Conservatories Curbs Curved eave construction Curved roof greenhouse Cypress (pecky) ng D Double glass sash Drip gutter . PAGE 164 191 179 190 24 3 24 3,26 78 242 255 256 248 251 249 246 247 254 3 156 60 59 n 15 1Z Eave plate Even span greenhouse Expansion tank (id 51 181, 187 Fire surface of boilers . Flow pipe, how to find size of Flues size and height of Forcing boxes Forcing houses Foundations Framework classes of erecting Framing Fuels 202 175 223 225 29 3,6 83 80 79,92 78, 85. 89 218 Gable raftet 73 INDEX 265 PAGE Gable roof sash-bed .... 30 Gearing, ventilator .... 131 Glass grades of . . . . , . 98 quantity in box .... 99 sizes of ..... . 100 substitutes for .... 113 Glazing ...... 97 butted method .... 102 lapped method .... 101 window and greenhouse . 105 Glazing bars ...... 68 Glazing points ..... 109 Glazing ladders ..... 120 Glazing sill ...... 65 Grate surface ..... 201 Greenhouses architecture of ... . 50 arrangement of ... . 36 circular ...... 62 curved eave ..... 62 curved roof ..... 59 erection of .... . 94 even span ..... 51 evolution of . 5-9 framing ...... 78, 85, 89 glass for ..... 97 heating ...... 158 lean-to ...... 50 location of . 35 plans and estimates for . 259 ridge-and-furrow .... 56 side hill ...... 60 size of ...... • 40 structural material for . . . . 63 ventilation of . 121 uneven span ...... 54 Gutter ........ 66 H Hanging rail, sash . . . . . 76 Heat, loss by reflection . . . . 42 Heating, greenhouse . . . . . 158 by hot water ...... 167 by steam ...... 188 coils ....... 164, 179, 191 combination systems . . . . 163 266 INDEX principles of . hot water vs. steam with cast iron pipes with flues High pressure steam heating Hotbed construction of described heating by flues location for manure for permanent, plans for sash for . temporary, plans for Hot twater heating advantages of arrangement of pipes for estimating radiation for general principles of pipe for . . . . pressure systems PAGE 158 159 164 159 196 10 2 23 11 21 19 11 20 159 159 169, 178 171,176 167 173 183 Irrigation overhead sub-irrigation Light loss by absorption loss by reflection Location for greenhouses for liotbeds Mats, sash-bed Manure for hotbeds L M 240 240 241 97 44 35 11 31 21 Paint estimating for iron work for . shading kinds of . Painting "Pecky" cypress 117 116 118 116 114 77 INDEX 267 PAGE Pipe covering- for ....... 218 frame . . . . . . . 64,88 paint for ....... 116 steel ........ 89 wrought iron . 89 Pit for hotbed ...... 17 Pitch of roof ....... 42, 45-46 Plans and estimates ..... 256 basis of ....... 257 detailed estimates for greenhouses 259 information required for 262 Plant forcers ...... 29 Pressure systems of hot water heating . 183 Propagating house ...... 4 Pumps capacity of ..... . 229 for circulating hot water 180 kinds of . 227 power required for ..... 229 steam . . . . . 198 Purlins ....... 74 Putty . 104 estimating ...... 107 liquid ....... 112 Putty bulb 108 R Radiation, how to estimate .... 171 Rafters n Rams, hydraulic . . . 232 capacity of ..... . 233 double acting ...... 236 plan for installing ..... 233 Range of glass, a . 5 Ridge ........ 75 Ridge-and-furrow houses .... 56 Roof, pitch of ..... . 42 S Sash ........ 11 cost of ...... . 13 glazing of ..... . 14 kinds of . 12 temporary ...... 16 Sash-bars ....... 69 spacing of ...... . ^1 368 INDEX Uneven span greenhouses U V 1 PAGE Sash-beds attached to dwelling .... 28 classes of ...... 2 gable roof ...... 30 materials, care of . 33 Sash sill ....... 65 Semi-iron frame houses .... 88 Shading , h ...... . 118 Shaft hangers ...... 130 Shafting, ventilator 128 Shed roof greenhouse . . . . . 50 Shutters ....... 33 Side hill greenhouse ..... 60 Side ventilating machinery .... 126, 134 Sliding shaft ventilating machine 140 Steam heating ...... 188 advantages of ..... 160 arrangement of boilers for 197 arrangement of coils for 191 coils for ...... 190 general principles ...... 188 high pressure ...... 196 vacuum and vapor systems 196 Steam pumps and traps .... 198 Stove house ........ 4 Structural material ..... 63 Substitutes for glass . . . . . . 113 . T Tanks capacity of . . ... 238 expansion ....... 181, 187 height of . . . . . 237 types of ....... . 236 Traps, steam return ...... 198 Truss framework ...... 91 34 Vacuum systems of heating . . , 196 Vapor systems of h eating , . 196 Ventilation , . o • . 121-141 overhead , , . , 124 side , . . , , 123 systems of , . , 124 under-bench , , . , 125 INDEX 2G9 PAGE Ventilators arms for . 136,138 header .... ... 1^ methods of hanging 126 size of . 126 Ventilating machinery- capacity of . . . 139 chain system . 133 closed column 132 gearing .... T31 open column . . . . 131 rack and pinion 133 shafting . . . . . 128 side .... . 134,136 sliding shaft . . . . 140 w Walks ashes used for concrete . construction of materials for . width of . Walls . . . Water supply amount used in greenhouses . cost of . hydraulic rams for raising pumps for .... storage tanks for Waterproofing for concrete Weather strip .... Wood, kinds used in greenhouse cons Wood frame greenhouses Wrought iron boilers Wrought iron pipe , ^ 156 , ^ 252 252 . 156 ^ ^ 155 . 83, 251 226 227 . 232 227-228 236 254 76 truction 77 . 85 . 205 • • « 89 ^ University of British Columbia Library DUE DATE NUV il \r^y' ii^ft2 3i974 1 c "^IBw ,Al ^' ■- APR 3 5 RCCU lMfe'6 2 3t -^ef ^ iBW srr^ TTm: FORM ><0 ' ^ FORESTRY AGRICULTURE LIBRARY ■i