Power burner-fluid condensing mode furnace

Abstract

A condensing mode furnace fired by a gun-type, power fluid fuel burner, such as an oil or gas burner, as a heat exchanger with a combustion chamber therein and communicating therewith. A duct carries the products of combustion from the heat exchanger to a thin and tube type condenser. An exhaust vent carries the products of combustion and condensate from the condenser, a drain line removing the condensate from the exhaust vent. A blower in the exhaust vent causes a flow of the products of combustion from the heat exchanger through the condenser and exhaust vent. An air passage surrounds the heat exchanger and condenser and a blower causes a flow of air serially over the condenser and heat exchanger to a hot air outlet. The furnace control initiates operation of the vent blower in response to a thermostat calling for heat in advance of operation of the burner thereby to purge on burned gases from the combustion chamber and heat exchanger. The vent blower remains in operation while the burner is in operation provide a draft for the burner so that the burner does not operate against a back pressure. The vent blower remains in operation under the control of the fan and limit switch after the thermostat has shut-down the burner in order again to purge unburned gases from the combustion chamber.