44 HEATING 



of the establishment in later years. The same remark 

 applies, and with greater force, to the heating plant. 



HEATING* 



In regard to heating, there are two general classes of 

 heating, namely, by hot water and by steam, which may 

 be divided into several different systems. Hot water is 

 the most generally used, as it will hold the heat for a 

 considerable length of time and has some drying effect on 

 the atmosphere, but not as much as steam. This system 

 of heating may be subdivided into two general classes: 

 (a) high pressure or closed system, and (b) low pressure 

 or open system. Low pressure is the most generally 

 used and requires an expansion tank, open to the air at 

 the highest point. High pressure is used in some cases 

 connected directly with the city water main. This system 

 has the advantage of a higher temperature than boiling 

 water on account of the outside pressure. In some cases a 

 circulation is used in order to accelerate the flow of the 

 water through the pipes. There are several different 

 appliances on the market. These may improve some 

 inferior hot water systems and thereby make a saving in 

 fuel. 



The most economical system on a place where a night 

 fireman is employed is steam. This system may be sub- 

 divided into three parts: (a) gravity, which is the most 

 common; (b) vacuum"; and (c) the trap system. 



The gravity system is more economical in a hilly 

 section where the boiler may be placed at the lowest point, 

 enabling the condensed water to run back to the boiler 

 and thus save the cost of pumping apparatus and its 

 maintenance. 



* By George H. Elliott, in The Florists' Exchange. 



