Abstract: A fuel-fired high capacity liquid heating appliance, representatively a boiler or a water heater, has a fluid heat exchanger extending around a combustion chamber into which first and second fuel burners extend, the first and second burners respectively having associated blowers for supplying combustion air thereto. Illustratively, the combustion chamber is oval-shaped, with the burners extending into opposite ends the combustion chamber If one of the burners is not firing while the other burner is firing, a control system starts the non-firing burner's blower, to protect it from overheating by the firing burner, if the control system senses an excess temperature in the non-firing burner. The heat exchanger comprises a series of fluid receiving tubes extending between baffle-free header structures iteratively sized to equalize fluid flow rates through the heat exchanger tubes over a wide flow rate range.

Abstract: A fuel-fired high capacity liquid heating appliance, representatively a boiler or a water heater, has a fluid heat exchanger extending around a combustion chamber into which first and second fuel burners extend, the first and second burners respectively having associated blowers for supplying combustion air thereto. Illustratively, the combustion chamber is oval-shaped, with the burners extending into opposite ends the combustion chamber If one of the burners is not firing while the other burner is firing, a control system starts the non-firing burner's blower, to protect it from overheating by the firing burner, if the control system senses an excess temperature in the non-firing burner. The heat exchanger comprises a series of fluid receiving tubes extending between baffle-free header structures iteratively sized to equalize fluid flow rates through the heat exchanger tubes over a wide flow rate range.

Abstract: A variable firing rate fuel burner has a tubular body configuration defined by a central pilot tube coaxially circumscribed by intermediate and outer firing tubes. A pilot fuel-air mixture is flowed through the pilot tube and ignited to maintain a pilot flame at the open outlet end of the burner body. During firing of the burner, separate fuel-air mixtures are flowed through an intermediate annulus between the intermediate firing tube and the pilot tube, and an outer annulus between the intermediate firing tube and the outer firing tube. As these fuel-air mixtures exit the burner body they are ignited by the pilot flame, with the fuel-air mixture exiting the outer annulus serving as a flame shaping mechanism to provide the overall burner flame with a controlled, elongated shape. By using two separate fuel-air mixture flows surrounding the pilot fuel-air mixture flow, the firing rate of the burner may be easily modulated, and the burner may be simultaneously operated with two different types of fuel.

Abstract: A variable firing rate fuel burner has a tubular body configuration defined by a central pilot tube coaxially circumscribed by intermediate and outer firing tubes. A pilot fuel-air mixture is flowed through the pilot tube and ignited to maintain a pilot flame at the open outlet end of the burner body. During firing of the burner, separate fuel-air mixtures are flowed through an intermediate annulus between the intermediate firing tube and the pilot tube, and an outer annulus between the intermediate firing tube and the outer firing tube. As these fuel-air mixtures exit the burner body they are ignited by the pilot flame, with the fuel-air mixture exiting the outer annulus serving as a flame shaping mechanism to provide the overall burner flame with a controlled, elongated shape. By using two separate fuel-air mixture flows surrounding the pilot fuel-air mixture flow, the firing rate of the burner may be easily modulated, and the burner may be simultaneously operated with two different types of fuel.