Furnace monitoring and control based on rate of flue gas temperature change
AssigneeCarrier Corporation
InventorPaul M. Haydock
Life of this patent
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Abstract
An illustrative example embodiment of a method of operating a furnace configured for heating a space to be occupied by at least one individual includes determining a rate of change of a flue gas temperature of a flue gas vented from the furnace, determining a difference between the determined rate of change and a predetermined acceptable rate for a current furnace operating condition, and adjusting at least one operation characteristic of the furnace based on the determined difference satisfying at least one predetermined criterion. In some situations, such as a heating cycle, the flue gas temperature is compared to maximum and minimum thresholds.
Claims20
A method of operating a furnace configured for heating a space to be occupied by at least one individual, the method comprising:
- determining a rate of change of a flue gas temperature of a flue gas vented from the furnace;
- determining a difference between a determined rate of change and a predetermined acceptable rate for a current furnace operating condition, wherein the predetermined acceptable rate comprises an increase in the flue gas temperature over time, and wherein the current furnace operating condition is a startup procedure that includes turning on a burner of the furnace;
- adjusting at least one operation characteristic of the furnace based on the determined difference satisfying at least one predetermined criterion, wherein the at least one predetermined criterion includes a rate difference threshold, and adjusting the at least one operation characteristic includes at least temporarily shutting down the furnace followed by automatically recycling the startup procedure when the determined rate is below the predetermined acceptable rate and the determined difference exceeds the rate difference threshold;
- and
- wherein at least temporarily shutting down the furnace followed by automatically recycling the startup procedure comprises performing the shutting down and recycling the startup procedure up to a predetermined acceptable number of times and subsequently preventing operation of the furnace based on the determined rate remaining below the predetermined acceptable rate and the determined difference repeatedly exceeding the rate difference threshold each of the number of times.
A furnace configured for heating a space to be occupied by at least one individual, the furnace comprising:
- a burner;
- a heat exchanger situated near the burner;
- a blower configured to direct fluid flow across the heat exchanger;
- a vent configured to direct flue gas away from the furnace;
- a temperature sensor situated to sense a temperature of the flue gas, wherein the temperature sensor is associated with a furnace component housing that is upstream from the vent;
- a controller that receives an indication of the temperature of the flue gas from the temperature sensor, the controller being configured to
- determine a rate of change of the flue gas;
- determine a difference between a determined rate of change and a predetermined acceptable rate for a current furnace operating condition;
- and
- adjust at least one operation characteristic of the furnace based on a determined difference satisfying at least one predetermined criterion;
- and
- wherein:
- the current furnace operating condition is a startup procedure that includes turning on the burner;
- the predetermined acceptable rate comprises an increase in the flue gas temperature over time;
- the at least one predetermined criterion includes a rate difference threshold;
- when the determined rate is below the predetermined acceptable rate and the determined difference exceeds the rate difference threshold, the controller is configured to adjust the at least one operation characteristic by at least temporarily shutting down the furnace followed by automatically recycling the startup procedure;
- and
- at least temporarily shutting down the furnace followed by automatically recycling the startup procedure comprises performing the shutting down and recycling the startup procedure up to a predetermined acceptable number of times and subsequently preventing operation of the furnace based on the determined rate remaining below the predetermined acceptable rate and the determined difference repeatedly exceeding the rate difference threshold each of the number of times.
Dependencies are inferred from the claim text.