Patent ID: 8267051

Claim:
A water heater comprising: a combustion housing having an exhaust opening at an upper end thereof, which is connected to an exhaust duct extending to outdoors; a burner unit which is stored in a lower part of the combustion housing and made up of a plurality of burner groups; a heat exchanger for hot water supply which is stored in an upper part of the combustion housing; an air supply fan for supplying combustion air to the burner unit via an air supply chamber provided on a lower side of an arrangement section of the burner unit in the combustion housing; and a capacity changeover mechanism for changing over combustion capacity by changing the number of burner groups to be burned, wherein the air supply chamber is divided into a plurality of parts corresponding to the plurality of burner groups, and comprises an air supply changeover mechanism for supplying air from the air supply fan to only a part of the air supply chamber corresponding to a burning burner group.