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Fuel-fired modulating furnace calibration apparatus and methods

  • US 5,865,611 A
  • Filed: 10/09/1996
  • Issued: 02/02/1999
  • Est. Priority Date: 10/09/1996
  • Status: Expired due to Term
First Claim
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1. Heat transfer apparatus subjectable to a variable heat transfer demand load and comprising:

  • recirculating means for recirculating a fluid medium through a flow path;

    first adjustment means associated with said recirculating means and operable to selectively vary the mass flow rate of the fluid medium through said flow path;

    a heat exchanger interposed in said flow path to be traversed by fluid medium flowing therethrough;

    fuel-fired means, connected to said heat exchanger, for receiving fluid fuel from a source thereof and utilizing the received fuel to create a heat exchange between said heat exchanger and the fluid medium traversing said heat exchanger and a corresponding temperature change in the fluid medium traversing said heat exchanger;

    second adjustment means associated with said fuel-fired means and operable to selectively vary the amount of fluid fuel received by said fuel-fired means; and

    calibration and control means for automatically adjusting each of said first and second adjustment means to accommodate changes in said variable heat transfer demand load, said calibration and control means being operative to;

    set one of said first and second adjustment means to a predetermined calibration setting thereof,calculate a theoretical setting for the other of said first and second adjustment means based on an assumed relationship between the setting of said second adjustment means and the resulting magnitude of heat transfer between said heat exchanger and the recirculating fluid medium,adjust said other of said first and second adjustment means to said theoretical setting,determine the actual fluid medium temperature differential resulting from said calibration and theoretical settings,change the determined actual fluid medium temperature differential to a desired fluid medium temperature differential magnitude by adjusting one of said first and second adjustment means to a second setting thereof,use the settings of said first and second adjustment means with the fluid medium temperature differential at said desired magnitude thereof to determine the actual relationship between the setting of said second adjustment means and the resulting magnitude of heat transfer between said heat exchanger and the recirculating fluid medium,utilize the determined actual relationship between the setting of said second adjustment means and the resulting magnitude of heat transfer between said heat exchanger and the recirculating fluid medium to establish a correlation between the settings of said first and second adjustment means which will maintain the desired fluid medium temperature differential magnitude,alter the setting of one of said first and second adjustment means in response to a change in heat transfer demand load for said heat transfer apparatus, andalter the setting of the other of said first and second adjustment means in accordance with the established correlation between the settings of said first and second adjustment means.

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