Patent ID: 7744366
Filing Date: 2010-06-29
Classification: F23N

Abstract:
1. A system for improving the thermal efficiency of a heating apparatus, the system comprising: a burner for receiving a combustion mixture; an igniter for igniting the combustion mixture; a means for modulating a fuel-input rate to the combustion mixture; a combustion air blower for controlling a quantity of combustion air flow to the combustion mixture; an alternating current electric motor operable within a range of speeds in a slip mode of operation for operating the combustion air blower, wherein the speed in the slip mode increases in response to an increase in the fuel-input rate of the system, wherein the alternating current electric motor includes a synchronous mode of operation, the electric motor operating at a synchronous speed when in the synchronous mode; and a switch for switching between the synchronous mode and the slip mode, wherein the electric motor switches to the synchronous mode in response to the fuel-input rate reaching a set value, wherein the quantity of combustion air flow from the combustion air blower in the synchronous mode is determined by the synchronous speed.