THE BALANCED DRAFT SYSTEM OF FURNACE REGULATION 



IT is a noteworthy fact that many of the modern 

 skyscraper office buildings, as well as the big 

 industrial steam plants and power houses 

 throughout the country, are equipped with the Bal- 

 anced Draft System of Furnace Regulation, under 

 patents owned by The Engineer Company, No. 50 

 Church Street, New York. 



The large buildings in lower Manhattan contain 

 more than 15,000 H. P. of steam boilers equipped 

 with the Balanced Draft System. This system auto- 

 matically controls the air supplied to the furnace and 

 limits it to practically the theoretical amount required 

 to burn enough coal to maintain steam pressure. 

 Any excess of air beyond this amount would dilute 

 the gases, reduce the furnace temperature and, con- 

 sequently, the efficiency of the furnace and boiler. 



In order to attain this limiting of the air supply, 

 the draft is "balanced" and atmospheric pressure is 

 maintained in the furnace chamber at the fire door. 

 So long as this condition is maintained, only enough 

 air to support combustion passes through the bed of 

 fuel and no excess is drawn in through the open door 



c 



or through cracks and crevices in the brick work 

 above the grate. This balance is automatically main- 

 tained for all rates of combustion and all conditions 

 of the fire. 



The Balanced Draft System reduces the fuel bills, 

 by limiting the amount of coal burned to the minimum 

 necessary to keep up the boiler pressure, irrespective 

 of the amount that is fed into the furnace. 



In the combustion of fuel in a steam-boiler furnace 

 two elements are to be considered: the fuel and the 

 air. The latter is supplied by either natural or 

 artificial draft and is either drawn or forced through 

 the furnace. In the ordinary boiler furnace, the 

 lack of correspondence between the air supplied and 

 the varying load on the boiler causes much waste 

 of coal, even with mechanical stokers or good hand 

 firing. Every pound of coal burned on the grate 

 needs just so much air to make it give the maximum 

 intensity of heat. Under ordinary conditions the air 

 supplied is controlled by regulating either the suction 

 of the chimney or the pressure of the forced draft. 

 With Balanced Draft, both the air supplied to the 



