Patent ID: 7241135

Claim:
In a burner control system having a gas supply, a gas valve for receiving gas from the gas supply and for controlling a gas pressure provided by the gas valve, an air source to be mixed with the gas provided by the gas valve to produce a gas/air mixture, a burner for producing a flame from the gas/air mixture resulting in a burning or burned gas/air mixture, a flame rod for detecting the presence of the flame produced by the burner, a heat exchanger for receiving the burning or burned gas/air mixture, a combustion fan for driving air from the air source such that it is be mixed with the gas provided by the gas valve and for driving the burning or burned gas/air mixture through the heat exchanger, the improvement comprising: a controller for receiving a signal from the flame rod and for producing a control signal to the gas valve in accordance with a predetermined relationship between the flame rod signal and the gas pressure provided by the gas valve so as to position the gas valve in accordance with a desired gas pressure, and wherein the controller provides for calibration of the flame rod from time to time by setting the gas valve at a maximum open position to produce a known regulated gas pressure, and then detecting a corresponding flame rod signal, the controller further determining a measure of the gas pressure produced by the gas valve at a less than maximum open position by correlating the flame rod signal that is measured at the less than maximum open position with a corresponding a gas pressure value.