FURNACE WITH MODULATING FIRING RATE ADAPTATION

摘要

A furnace is disclosed that includes a burner with a firing rate that is variable between a minimum and a maximum firing rate. After a call for heat is received, the firing rate is set to an initial level above the minimum firing rate, and the burner is ignited. The firing rate is then modulated downward toward the minimum firing rate. If the flame is lost during or after modulation, the burner is reignited and the firing rate is maintained above the firing rate at which the flame was lost until the current call for heat is satisfied. In some cases, the firing rate is maintained until one or more subsequent calls for heat are satisfied.

主权项

1. A method of operating a combustion appliance that has a burner and three or more different firing rates including a minimum firing rate, a maximum firing rate and at least one intermediate firing rate between the minimum firing rate and the maximum firing rate, the combustion appliance further includes a variable speed combustion blower, wherein each of the three or more firing rates is associated with a different corresponding combustion blower speed, the method comprising:
determining that a flame is lost during operation of the combustion appliance; after it is determined that the flame was lost, initiate a calibration cycle, wherein the calibration cycle comprises:
changing the combustion blower speed of the variable speed combustion blower until a first predetermined flow rate of combustion air is detected;determining a first combustion blower speed that corresponds to when the first predetermined flow rate of combustion air is detected;changing the combustion blower speed of the variable speed combustion blower until a second predetermined flow rate of combustion air is detected;determining a second combustion blower speed that corresponds to when the second predetermined flow rate of combustion air is detected; andre-calibrating the different corresponding combustion blower speeds for each of a plurality of the three or more firing rates based on the first determined combustion blower speed and the second determined combustion blower speed.