HEATING THE RANGE 



107 



one-half inch pipe being equivalent to one and five-hun- 

 dredths square feet of surface, and one linear foot of one 

 and one-quarter inch pipe being equivalent to forty-three 

 hundredths square feet of surface. This difference of the 

 comparative values of hot-water and steam heating sur- 

 faces is due to the fact that greenhouse heating systems 

 are called on for their very hardest work at night, and 

 dwelling house conditions require the most heat in the 

 daytime; and again a greenhouse hot-water plant gets 

 little or no attention for hours at night, while a steam 

 heating system requires a night fireman. To be brief, 

 there is less difference in night and day temperatures of 

 steam pipe than there is in night and day temperatures 

 of hot- water pipe." 



SYSTEMS OF GREENHOUSE HEATING 



a. Open tank gravity 



A. 



Hot- 

 water 



3^" cast-iron pipe. 

 2" wrought-iron pipe. 



b. Closed tank or pressure 



c. Forced circulation : 



1. Water heated 

 in cast-iron 

 boiler. 



2. Water heated 

 in converter 

 or feed water 

 heater. 



3. Water heated 

 in tubular 

 water boiler. 



a. Low pressure with gravity return. 

 6. Low pressure with return by steam trap, 

 c. High pressure at boiler, with reduced pressure in 

 greenhouses, and pumped return. 



83. Open tank gravity hot-water heating. --" It has 

 been mentioned that there are over-bench and under- 



B. 



Steam 



Propeller driv- 

 en by electricity, 

 centrifugal or ro- 

 tary pump driven 

 by steam, elec- 

 tricity, gas or oil 

 engine; piston 

 pump driven by 

 steam. 



" rust caulked " 

 joints or screwed 

 joints. 



