Patent ID: 8740611

Claim:
Fuel-fired liquid heating apparatus comprising: a heat exchanger through which a liquid to be heated may be flowed; first and second fuel burners operable to receive fuel and combustion air from sources thereof and create hot combustion products used to transfer combustion heat, via said heat exchanger, to liquid flowing through said heat exchanger; first and second combustion air blowers respectively associated with said first and second fuel burners and operable to supply combustion air thereto for mixture with fuel supplied to said first and second fuel burners from a source other than said first and second combustion air blowers; and a control system automatically operable in response to (1) non-firing of one of said first and second fuel burners and (2) firing of the other of said first and second fuel burners, to protect the non-firing burner against being overheated by heat from the firing burner by sensing a temperature of the non-firing burner and responsively starting its associated combustion air blower to cool the non-firing burner when the sensed temperature reaches a predetermined magnitude.