Patent ID: 8770153
Filing Date: 2014-07-08
Classification: F23N,F24H,Y02B

Abstract:
1. A water heater comprising: a burner; a fan for supplying air for combustion; a heat exchanger including a housing into which combustion gas is supplied together with air, and a water tube recoverable of sensible heat and latent heat from the combustion gas, and at least a portion of the water tube disposed in the housing; and a controller including a data table and controlling the fan based on the data stored in the data table wherein: plural kinds of fan-controlling data are stored in the data table; the plural kinds of the fan-controlling data include a first period during which condensate is not substantially generated on a surface of the water tube, a second period during which condensate gradually increases on the surface of the water tube and a third period during which generated condensate is stabilized, the first period and the second period being periods during which the combustion gas generated by the burner is supplied from the burner into the heat exchanger; the rotational speed of the fan is at a constant predetermined first rotational speed during the first period, rotational speed of the fan is at a constant predetermined second rotation speed during the third period, the constant predetermined first rotational speed being slower than the constant predetermined second rotational speed and the rotational speed of the fan is continuously increased with time from the constant predetermined first rotational speed to the constant predetermined second rotational speed during the second period; the plural kinds of fan-controlling data are defined corresponding to at least one of a combustion level by the burner and temperature of water entering the heat exchanger; and each one of the fan-controlling data includes data for stopping the increase of the rotational speed of the fan when the third period starts after completion of the second period, the third period being a period during which the combustion gas generated by the burner is supplied from the burner into the heat exchanger.