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 



