Burner firing rate determination for modulating furnace

• US 8,123,518 B2
• Filed: 07/10/2008
• Issued: 02/28/2012
• Est. Priority Date: 07/10/2008
• Status: Active Grant

• Current Assignee: Ademco Inc. (Resideo Technologies, Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: Nordberg, Timothy J., Schultz, Michael W., Bird, Douglas D., Chiain, Brent
• Primary Examiner(s): Rinehart, Kenneth
• Assistant Examiner(s): Corboy, William
• Application Number:
  US12/171,158
• Publication Number:
  US 20100009302A1
• Time in Patent Office: 1,328 Days
• Field of Search: 236/10, 236/11, 431/12, 431/75, 126/116.A, 126/110.A, 126/110
• US Class Current: 431/12
• CPC Class Codes: F23N 1/02 conjointly with air supply
• CPC Class Codes: F23N 2223/54 Recording
• CPC Class Codes: F23N 2227/02 Starting or ignition cycles
• CPC Class Codes: F23N 2227/10 Sequential burner running
• CPC Class Codes: F23N 2237/10 High or low fire
• CPC Class Codes: F23N 2241/02 Space-heating
• CPC Class Codes: F23N 5/203 using electronic means

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.

Claims

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.

2. The method of claim 1, further comprising resetting the first stage ON parameter to zero at the end of the current heating cycle.

3. The method of claim 1, further comprising resetting the second stage ON parameter to zero at the end of the current heating cycle.

4. The method of claim 1, further comprising storing a final calculated burner firing rate when a previous heating cycle ends.

5. The method of claim 4, wherein calculating the burner firing rate based on the first stage ON time and the second stage ON is also based at least in part on the stored calculated burner firing rate.

6. The method of claim 1, further comprising resetting the first stage ON parameter to zero at the end of the current heating cycle, and resetting the second stage ON parameter to zero at the end of the current heating cycle.

7. A method of operating a forced air furnace having a variable rate burner and a controller, the method comprising the steps of:

receiving a call for heat;

determining an initial burner firing rate according to the formula;

8. The method of claim 7, wherein the call for heat includes a W ON signal from a single-stage thermostat.

9. The method of claim 7, wherein the call for heat includes a W1 (first stage heat) ON signal from a two-stage thermostat.

10. The method of claim 9, wherein the call for heat further comprises a W2 (second stage heat) ON signal from the two-stage thermostat.

11. The method of claim 7, further comprising stopping the burner if the call for heat ceases.

12. The method of claim 7, wherein adjusting the burner firing rate after the predetermined period of time comprises increasing the burner firing rate by a determined amount at selected one or more predetermined intervals.

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:

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;