Steam and Hot Water for Greenhouse Heating, 185 



hot water, or to mechanical differences in the two heaters. Fowlei'* 

 considers steam cheaper than hot water in coal consumption, 

 chie% because excess of heat is shut of in the steam pipes, and 

 steam heatera are commoidy provided ^^'ith automatic regulators. 

 Our steam heater ha® an automatic regulator, while the hot water 

 has not. 



5. Influence of pressure upon the temperature of steam pipes. — 

 While it is true that the greater the pressure iudicated by the 

 steam gauge, the more readily is the steam carried through long 

 runs and past obstacles, the influence of this pi'essure upon the 

 temperature of the pipes is not so obvious. Table V shows the 

 influence of pressure upon the temperatm*e of risers and returns: 



* Hints on the Heating of Greenliouses, 31 



24 



