Greenhouse Heating 



the general efficiency and easy control of the plant would be so much 

 increased, that such loss should not be considered as a bar to its use. 



Such a plant could be made a combination steam and water installa- 

 tion, using steam in cold weather and water in mild weather. As a tem- 

 perature of 200 to 230 degrees Fahr. could be readily maintained throughout 

 the entire radiation surface by water, there seems to be little reason for 

 making steam a factor in it. There would, theoretically, be less friction in 

 the steam, though air valves and joints would bring the two systems about 

 on a level as to economy. 



With care and watchfulness, a temperature of 280 degrees would be 

 entirely practicable at fifty pounds pressure. Given an installation of this 

 design, to start with you have an apparatus perfectly adapted to all weath- 

 ers; in mild weather, a slow fire and a slow movement of the pump; in 

 cold weather, a rapid fire and a more rapid movement of the pump. 



In this installation the pipes could be of the same size throughout as 

 with the steam system, with the material advantage that the mains could 

 be run practically at will, and with less regard to location, than with the 

 usual gravity system. With the usual valves, the fireman would have per- 

 fect control over his entire system. The loss of heat units in the power 

 required to move the water through the apparatus would probably be no 

 more than is absorbed by the pump in lifting and returning the water of 

 condensation in the positive return steam apparatus. 



Steam Heating Systems 



There are three systems of steam heating which are common among 

 florists : First, the Gravity System; second, the Positive Return System; 

 third, the Vacuum System. 



The Gravity Method 



The gravity system, as its name implies, is dependent on the weight 

 of its condensed steam, or water, for the proper return of such condensa- 

 tion to the boiler, and is, perhaps, the most desirable of all systems for the 

 average florist. Indeed, this is the only steam-heating system which fully 

 meets the necessities and numerous exactions of the florist who does not 

 employ a night fireman, his requirement being a simple apparatus which 

 needs comparatively little attention, and which should, in a measure, be 

 automatic in action. The radiating surface should be readily controlled by 

 the operator. The boiler should be easy to fire, and the entire apparatus 

 durable, with no features in construction likely to need frequent or costly 



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