694 GREENHOUSE 



if they must be employed, special hot-water fittings 

 should be SfClired. 



Ill c i\;it"ii. - ,\iili hi^'li side walls, it is desirable 



to pla' ■ I' I' ' j : :ii 111" idate and the returns on 

 the w.,1. . r i ,. iiM .. Fifjs. 1001, 1002 and 1003 



rose and viulet house. 



Hot Water Under Presstire.— In some large Green- 

 houses the hot water systems have been placed under 

 pressure by closing the expansion tank. To prevent any 

 danger of the blowing up of the system, a safety-valve, 

 with a weight set so as to allow the water to escape be- 

 fore the danger point is reached, is attached either to the 

 tank or expansion pipe. The system being completely 

 closed, the water as it warms is placed under pressure, 

 and steam cannot be formed. This makes it possible to 

 raise the temperature of water in the coils quite a num- 

 ber of degrees higher than when an open tank is used. 

 As there is even more danger from an explosion of a 

 system when the water is under pressure than when 

 steam is used, care should be taken to see that the safety- 

 valve is in good working order, and that it is set at a 

 point well below the danger limit. 



When water is carried under pressure, it permits of 

 the use of smaller flows and returns, and a considerable 

 reduction in the amount of radiating surface. On the 

 other hand, it is less economical in fuel than the open 

 system, and requires rather more attention. The pressure 

 system cannot be recommended for use under all condi- 

 tions, and it will generally be best to have the piping 

 adapted for all except the most severe weather, and then 

 to have it so arranged that the system can be closed, if 

 it becomes necessary to do so in order to maintain the 

 desired temperature. 



Piping for Steam. — The arrangement of th 

 heating pipes for use with steam need not be 

 unlike that above described for hot water, 

 except that smaller flow and return pipe; 

 are used. When there is but one or 

 two houses it is well to use over- 

 head flow pipes, as a rule only 

 one being required in a house. 

 A 2-inch flow pipe will be suf- 

 ficient for 400 square feet of 

 radiation, and 2K-, 3-, 3K- and 

 4-ineh supply pipes will an- 

 swer, respectively, for 700, 

 1,000, 1,400 and 1,900 square 

 feet of radiation. For long 

 houses it will be best to use 

 IM-inchpipe for the coils, but 

 1-inch pipe will answer for 

 houses 100 feet or less in length 



GREENHOUSE 



3 where 50°, 60° and 70°, respectively, are required. 

 Fig. 1004 illustrates piping for steam in a rose house. 



Heating by J'Jiies. — Where fuel is cheap, and when 

 either a low temperature is desired in the house or the 

 outside temperature does not drop much below the 

 freezing point, hot-air flues may be used, but while the 

 cost of constructing them is not large, the danger from 

 fire is so great that they are not always economical. A 

 brick furnace is built at one end of the house, and from 

 this a 10- or 12-inch flue is constructed to carry the 

 smoke and hot gases through the house to the chiiimey, 

 which may be at the farther end, or directly over tlie 

 furnace, the flue in the latter case making a complete 

 circuit of the house. When the houses are more than 

 60 feet long, it is advisable to have a f'nrnn<-e at each 

 end, and the flue will then extend mily i.. tli" .-. mn- of 

 the house and return to the end frum \\li|rli ii vi.ut.d. 

 The first 30 feet of the flue should 1.. ■ l lin Im i-k. Imt 

 beyond that it can be constructed of siwcr \>\\>i-. While 

 either hard or soft coal may be used, the best results 

 will be secured with 3- or 4-foot lengths of hard wood. 

 Where the temperature does not drop more than 10 or 12° 

 below zero, a temperature of 40° may be maintained in 



1002. Rose house, 150 x 20 ft., piped for water. 



The coils should, of 

 course, run down hill, but if overhead supply pipes are 

 not used the connection may be made at the end of the 

 house nearest the boiler and the return pipe may be 

 placed underneath the coil. In order to prevent the 

 water from backing up in the coils it is desirable that 

 they should be at least 18 or 20 inches above the level of 

 the water in the boiler, while 3 or 4 feet would be even 

 better. There should be an automatic air valve at the 

 lower end of each coil, and, in order to regulate the 

 amount of steam, a shut-off valve should be placed in 

 both flow and return pipes. Unless there are several 

 coils in each house it will always be well to have valves 

 upon a number of the pipes in the coils, so that all but 

 one or two can be cut ofl' if desired. To prevent the 

 water from being forced out from the boiler when the 

 steam is turned into the houses, there should be a check 

 valve in the return pipe near the heater. 



The amount of radiation which will he required to se- 

 cure any desired temperature will v.iry t.. -...me extent 

 with the amount of pressure tli:il i- larrjnl in the boiler, 

 but, as a rule, this is not more tliaii li\ . |...iiii.|v. no. I .if ten 

 no pressure at all is used. It will ..r.liiiarily he best to 

 have the radiation sufficient to furnish the "temperature 

 desired in ordinarily cold weather without carrying any 

 pressure, and then by raising the pressure to from five 

 to ten pounds secure the heat that is needed during cold 

 waves. 



In determining the amount of radiation for a steam- 

 heated house, 1 square foot of pipe will answer for 9 

 square feet of glass, when 40° is desired, and for 7, 5 and 



a house 20 feet wide with one circuit of 12-inch sewer 

 pipe. Care sh..nl.l b.- taken that the flue in no place is 

 in contact witli w ...i.Iw..ik, and that there is a gradual 

 rise in the ilu. fi-. .nj ili.. |..iint where it leaves the fur- 

 nace to wh. !.■ It . iit.r. the chimney. l. H. Taft. 



Greenhouse Management. — Persons usually learn to 

 grow plant-, iiii.lir i;his-i by rule of thumb. Such knowl- 

 edge is alway-. es-;eiitial. tnit better and quicker results 

 are obtaiui-.l if tin. h living truths or principles are 

 learned ;it ttn v;nii.- titm-. Even if no better results in 

 plant-growiii- " ■ i. t.i I btained, the learning of prin- 

 ciples coul.l ii.\ . r .1.. hanii, and it adds immensely to the 

 intellectiKil sati^la.-ti.ui in the work. There is no Ameri- 

 can writing which essays to expound the principles of 

 Greenhouse management, although there are excellent 

 manuals giving direct advice for the growing of various 

 classes of plants. The best single recent American 

 book in this line is Taft's "Greenhouse Management," 

 which brings together in one volume concise directions 

 for the growing of the leading kinds of Greenhouse 

 subjects. There are two kinds of principles to appre- 

 hend in Greenhouse management,— those relating to 

 the management of the plants themselves, and those 

 dealing primarily with the management of the house. 



The first principle to be apprehended in the growing 

 of plants under glass is this : Each plant has its ou-n 

 season of bloom. Every good gardener knows the times 

 and seasons of his plants as he knows his alphabet, 

 without knowing that he knows. Yet there are many 

 failures because of lack of this knowledge, particularly 



