Burner firing rate determination for modulating furnace
First Claim
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1. A method of operating a forced air furnace comprising a variable burner firing rate burner and a controller, the controller configured to accept signals from a two-stage thermostat, the method comprising the steps of:
- defining a first stage ON parameter based upon a length of time a W1 (first stage heat) ON signal is asserted by the two-stage thermostat during a current heating cycle;
defining a second stage ON parameter based upon a length of time a W2 (second stage heat) ON signal is asserted by the two-stage thermostat during the current heating cycle;
calculating a burner firing rate for the current heating cycle based, at least in part, on the first stage ON parameter and second stage ON parameter; and
operating the variable rate burner at the calculated burner firing rate.
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Abstract
A modulating furnace having a variable rate burner and a controller is operated at a first burner firing rate for a first period of time, and a higher burner firing rate once the first period of time has expired. In some instances, the burner may be operated only while the controller is receiving a call for heat from a thermostat or the like.
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Citations
13 Claims
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1. A method of operating a forced air furnace comprising a variable burner firing rate burner and a controller, the controller configured to accept signals from a two-stage thermostat, the method comprising the steps of:
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defining a first stage ON parameter based upon a length of time a W1 (first stage heat) ON signal is asserted by the two-stage thermostat during a current heating cycle; defining a second stage ON parameter based upon a length of time a W2 (second stage heat) ON signal is asserted by the two-stage thermostat during the current heating cycle; calculating a burner firing rate for the current heating cycle based, at least in part, on the first stage ON parameter and second stage ON parameter; and operating the variable rate burner at the calculated burner firing rate. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of operating a forced air furnace having a variable rate burner and a controller, the method comprising the steps of:
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receiving a call for heat; determining an initial burner firing rate according to the formula; - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method of operating a forced air furnace comprising a variable burner firing rate burner and a controller, the controller configured to accept signals from a two-stage thermostat, the method comprising the steps of:
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defining a second stage ON parameter based upon a length of time a W2 (second stage heat) ON signal is received; calculating a burner firing rate for a current heating cycle based, at least in part, on the second stage ON parameter; operating the variable rate burner at the calculated burner firing rate; wherein calculating the burner firing rate comprises calculating a burner firing rate according to the formula;
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Specification