GREENHOUSE HEATING 159 



Heating with Flues. In heating with 

 flues the equipment consists simply of a 

 furnace at one end of the house and a chim- 

 ney at the other, the two being connected by 

 a flue, carried underneath the bench or 

 buried just underneath the soil, through 

 which the heat and smoke are carried. This 

 may be made of brick, but large-size drain 

 or sewer tile are more commonly used. These 

 withstand the heat and are easily and cheap- 

 ly put in place. It is best to have the flue 

 slope upward slightly toward the chimney. 

 As has already been stated, this method is 

 wasteful of fuel. It is also difficult to regu- 

 late. It is still employed to some extent 

 by vegetable gardeners in cheap houses, 

 used only in late winter or early spring for 

 the starting of early vegetable plants, sweet 

 potatoes, etc. 



Hot Water vs. Steam. There has been 

 much discussion as to the relative virtues of 

 hot water and steam for use in greenhouse 

 heating. It may be well to consider here 

 some of the advantages claimed for each. 

 For hot water the following are claimed: 



(1) It provides a more even heat than steam. 



(2) The radiating pipes are not so hot, and 



