Patent ID: 8635997

Claim:
A system for controlling gas pressure to a gas-fired appliance, the system comprising: a modulating gas valve for supplying a controlled amount of gas to a burner unit; a multi or variable speed inducer fan situated downstream of the burner unit and configured to produce a combustion air flow in the burner unit and out through a vent pipe; a pressure reducing element situated downstream of the burner unit and in fluid communication with the inducer fan and the vent pipe, the pressure reducing element configured to output at least one pneumatic signal that is related to said combustion air flow, the pressure reducing element providing the at least one pneumatic signal to the modulating gas valve, wherein the modulating gas valve is configured to amplify the at least one pneumatic signal and modulate the amount of gas supplied to the burner unit based on the amplified at least one pneumatic signal; and an appliance controller for receiving one or more control signals from a thermostat, and for controlling the speed of the inducer fan based at least in part on the one or more control signals.