Heating ivith Pipes and Flues 



351 



218. Pipe-heated hotbed. 



underneath the heels. The pipes should not he surrounded 

 by earth, hut should run through a free air space. 



A flue-heated or pipe-heated hothed may he likened to a 

 greenhouse bench, and the arrangement of pipin^]^ for the 

 two should be similar. 

 Two to four steam- or 

 water-pipes are carried 

 underneath the bed. If, 

 however, one has plenty of 

 exhaust steam, which is 

 usually under consider- 

 able pressure, it may be 

 carried directly through 

 the soil in ordinary drain 

 pipes. It will rarely pay to put in a hot water or steam 

 heater for the express purpose of heating hotbeds, for if 

 such an expense is incurred, it will be better to make a 

 forcing-house. 



Flue-heated beds. 



Hotbeds may be heated with hot-air flues with very 

 good results. A home-made brick furnace may be con- 

 structed in a pit at one end of the run and underneath a 

 shed, and the smoke and hot air, instead of being carried 

 directly upwards, are carried through a slightly rising 

 horizontal pipe which runs underneath the beds. For 

 some distance from the furnace, this flue may be made of 

 brick or unvitrified sewer j)i]^e, but stovepipe may be 

 used for the greater pa^^t of the run. The chimney is 

 ordinarily at the farther end of the run. It should be 

 high, to provide a good draft. If the run of beds is long, 



