| 摘要 |
PROBLEM TO BE SOLVED: To provide a hot water heater having a function of heat insulating operation which does not so much bring about lowering of the property of heat insulating operation of the hot water heater, and ensures durability and safety. SOLUTION: A hot water heater having a function of heat insulating operation at least comprises a cold water supply pipe 1, a hot water discharge pipe 2, a can 4 containing a heat exchanger 5 and a burner mechanism 6, and a temperature sensor 14 for detecting water temperature in the heat exchanger 5, and also comprises a function of heat insulating operation for carrying out heat insulating operation even when hot water is not supplied, by bringing the burner mechanism 6 into a combusting status. The hot water heater controls itself so that, during heat insulating operation, heat insulating combustion is started when the detected water temperature in the heat exchanger 5 becomes not more than the temperature for starting heat insulating combustion, and that heat insulating combustion is stopped when the water temperature in the heat exchanger 5 becomes not less than the temperature for stopping heat insulating combustion. There is provided a control unit 15 for changing a heat insulating combustion starting temperature, or both of the heat insulating combustion starting temperature and a heat insulating combustion stopping temperature, when the age of the hot water heater becomes a certain standard value or more, to temperatures which are lower than the temperatures in the case where the age is less than the specific value.
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