Patent ID: 7513221

Claim:
A water heater comprising: a water tank adapted to contain water to be heated; a flue extending through the water tank and having an inlet end and an outlet end; a combustion chamber in communication with the inlet end of the flue, the combustion chamber having an air intake defining an air inlet, said combustion chamber being substantially air-tightly sealed except for the air inlet and the inlet end of the flue; means for introducing air into the combustion chamber and raising the pressure of both primary and secondary air in the combustion chamber above atmospheric pressure; and a main burner within the combustion chamber and operable to combust a mixture of air and fuel to create products of combustion; wherein the products of combustion flow out of the combustion chamber into the inlet end of the flue, heat the water in the tank through the flue, and exit the water heater through the outlet end of the flue; wherein primary air is mixed with fuel prior to combustion at the main burner; wherein secondary air within the combustion chamber combines with the primary air and fuel mixture to complete the combustion process at an outlet of the burner.