US 3,964,675 AGranted

Appartus for limiting vacuum and pressure in a furnace

OwnerPerry C. Euchner, Jr.inventor

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Abstract

A furnace system having a combustion chamber, and heat transfer surfaces, forced and induced draft fans for moving gas through the burner, chamber, and heattransfer surfaces, first controls for maintaining predetermined gas flows and furnace pressure or draft dependent upon the desired normal operating conditions, and second controls responsive to the flow of the gas exterior to the chamber, e.g., at the inlet or outlet of the induced draft fan and, if desired, at the outlet of the forced draft fan, for controlling a damper or dampers in the gas path or the speed of the fans so as to limit the vacuum which can be developed in the chamber by the induced draft fan to a value less than the chamber vacuum withstanding design value. Also, if desired, the second controls at the outlet of the forced draft fan can limit pressure which can be developed in the chamber by the forced draft fan to a value less than the chamber pressure withstanding design value.

Claims11

Dependent claims

In a furnace system having a combustion chamber, fan means and duct means connected to said chamber for moving gas along a path extending from exteriorly of and into said chamber, through said chamber and then outwardly from and away from said chamber, said fan means including at least one fan having an inlet and an outlet and the gas pressure internally of said chamber being at least partially dependent upon the level of flow of the gas which is supplied to and removed from said chamber, said chamber being subject to damage when said gas pressure internally of said chamber reaches a predetermined value, gas flow modifying means in said path for modifying the flow of gas through said chamber and control means comprising measuring means in said path and connected to at least part of said gas flow modifying means for normally maintaining the flow of said gas at predetermined levels required for normal operation of said system, the combination therewith of gas flow measuring means in the path of said gas outside said chamber and adjacent said fan, said last-mentioned measuring means being responsive to changes in the flow of said gas at one of said inlet and said outlet, and gas flow limiting means interconnecting said last-mentioned measuring means and at least part of said gas flow modifying means for changing the flow of said gas from said predetermined levels to further predetermined levels which are dependent upon the rate of flow of said gas exteriorly of said chamber, said further predetermined levels being higher with an increasing rate of flow of said gas exteriorly of said chamber and lower with a decreasing rate of flow of said last-mentioned gas but being less than the gas flow level which will cause the gas pressure internally of said chamber to reach said predetermined value.

In a furnace system having a combustion chamber, fan means and duct means connected to said chamber for moving gas along a path extending from exteriorly of and into said chamber, through said chamber and then outwardly from and away from said chamber, said fan means comprising an induced draft fan and said duct means comprising an inlet duct interconnecting said fan with said chamber for removing said gas therefrom and an outlet duct connected to said fan, gas flow modifying means in said path for modifying the flow of gas through said chamber and control means comprising measuring means in said path and connected to at least part of said gas flow modifying means for normally maintaining the flow of said gas at predetermined levels, the combination therewith of gas flow measuring means in the path of said gas outside said chamber and responsive to changes in the flow of said gas, limiting means interconnecting said last-mentioned measuring means and at least part of said gas flow modifying means for changing the flow of said gas from said predetermined levels to further predetermined levels dependent upon the rate of flow of said gas exteriorly of said chamber, said further predetermined levels being higher with an increasing rate of flow of said gas exteriorly of said chamber, said gas flow modifying means comprising a variable damper in said inlet duct for varying the duct passageway size at said damper, said measuring means comprising a flapper pivotally mounted in said outlet duct adjacent to said fan and variable in position in accordance with the rate of flow of the gas in said outlet duct and said interconnecting means comprising mechanical means for varying said passageway size dependent upon the position of said flapper.

Dependencies are inferred from the claim text.