190 MASSACHUSETTS HORTICULTURAL SOCIETY. 



will produce more steam per ton than the anthracite. To be 

 "worked economically, the fire should have a strong draft, and be 

 frequently tended. It is a mistake to suppose, as many do, that a. 

 dull, slow fire is economical, for the coal is imperfectly consumed 

 in such a fire, and nearly half of its heating power goes up the 

 chimney as carbonic oxide. In small establishments, however, 

 where the saving in coal will not pay the wages of a night fireman, 

 it is necessary to burn anthracite and burn it slowly. 



The chief advantage of steam over hot water consists in the 

 ease with which the heat can be distributed just where and when 

 wanted. One of the best illustrations of this point that has come 

 under my notice is at the farm of Mr. E. N. Pierce, of Waverly, 

 where six large greenhouses are heated from one large boiler, by 

 means of 8,800 feet of one and one-quarter-inch pipe, branching 

 from a four-inch main. In this case the boiler is worked under a 

 pressure of about ten pounds of steam, and is set at a level of 

 about forty feet below the highest house, and about twelve feet 

 below the lowest one, so that the water from condensed steam in- 

 the radiating pipes returns to the boiler by gravity. The fireman 

 sleeps in a room over the boiler, which is provided with an electric 

 alarm that wakes him whenever the pressure of steam goes below 

 ten pounds per inch. 



In planning for steam heating, it is very important to have the 

 boiler set at a level low enough to drain the water promptly from 

 the radiating pipes, bearing in mind that the friction of the steam 

 in passing through a long system of circulation, together with the 

 condensation, will reduce the pressure, so there will often be 

 several pounds difference in pressure between the flow and return 

 pipes ; therefore the boiler must be set low enough to balance this, 

 or the water will accumulate in the pipes and they will cease to 

 radiate heat. Two feet head of water will balance about one 

 pound difference in pressure, and it is desirable for this reason to 

 have at least four or five feet difference of level between the 

 lowest heating pipes and the boiler. But no exact rule can be 

 given, since much depends on the size of the pipes used, their 

 length, and the consequent reduction of pressure. A good sized 

 main steam-pipe will do much to favor good circulation, and if it 

 radiates more heat than is wanted it can be wrapped with felt. 

 Much of the difficulty encountered in steam heating is due to 

 ignorance, or neglect of the principles above stated. 



