98 THE PRINCIPLES OF FLORICULTURE 



cause of increased glass area, a second sectional boiler 

 may be installed. 



77. Fuel. The selection of fuel depends largely on 

 the location and the size of the range. Different kinds 

 of fuel are less expensive in some sections than in others. 

 When a cheap grade of soft coal is used, it is most fre- 

 quently burned by forced draft. This is by a blower 

 which increases the rapidity of combustion. 



78. Arrangement of supply pipes. In the older 

 systems of steam heating, it was customary to have a 

 large " flow-pipe " which went to the farther end of the 

 house and there branched to supply various return coils. 

 In up-to-date ranges, this method is seldom used. In 

 the old systems, large flow-pipes were located near the 

 roof, with the result that much heat was lost unless the 

 pipes were packed in asbestos covering. This was be- 

 cause the heat was where it was not needed. Then again, 

 much shade was cast in the house by these flow-pipes. 

 The pipes are now so arranged that the steam, as it enters 

 the house, is dispersed through many small coils until it 

 reaches the farther end of the house. It then comes 

 into a trap, in case the end of the house is not high enough 

 to allow condensed steam to flow back to the boiler by 

 gravity. One and one-fourth inch pipes are used for the 

 flow and two-inch pipes for the return. If there are several 

 large houses, the steam leaves the boiler through a large 

 pipe. This extends through the connecting houses, and 

 as it passes each house, the steam necessary to heat that 

 house enters the small pipes. 



In a large, commercial, rose establishment which is 

 heated by steam, three one hundred and sixty-three horse- 

 power boilers are used to heat four houses, each of which 

 is five hundred feet long and forty-two feet wide. These 



