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- 



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