Gas pressure control for warm air furnaces

摘要

Systems, methods, and controllers for controlling gas-fired appliances such as warm air furnaces are disclosed. An illustrative furnace system can include a burner unit in communication with a combustion air flow conduit and heat exchanger, a variable speed inducer fan or blower adapted to provide a flow of combustion air to the burner unit, a furnace controller and motor speed control unit adapted to regulate the speed of the inducer fan or blower, and a pneumatically modulated gas valve adapted to variably output gas pressure to the burner unit based at least in part on the combustion air flow.

主权项

1. A method of controlling a gas-fired appliance, wherein the gas-fired appliance includes a burner unit, a heat exchanger, a gas valve, a multi or variable speed inducer fan that is configured to produce a combustion air flow through the burner unit and the heat exchanger, and a heated air blower configured to force air through the heat exchanger and to one or more warm air ducts, the method comprising:
a) setting the multi or variable speed inducer fan to a first fan speed to provide a combustion air flow through the burner unit; b) delivering an amount of fuel to the burner unit via the gas valve to form a combustion air/fuel mixture in the burner unit, wherein the amount of fuel that is delivered to the burner unit is dependent on the combustion air flow; c) igniting the combustion air/fuel mixture within the burner unit, if not already ignited; d) calculating a measure that is representative of a temperature of a predetermined air flow of the gas-fired appliance based, at least in part, on the first fan speed; e) adjusting the speed of the inducer fan or blower to an adjusted fan speed, wherein the adjusted fan speed is based, at least in part, on the calculated measure that is representative of the temperature of the predetermined air flow, resulting in an adjusted combustion air flow through the burner unit; and f) repeating steps b)-e) using the adjusted combustion air flow through the burner unit.