HOT WATER HEATING DEVICE

PROBLEM TO BE SOLVED: To perform intended defrosting also during stop of operation and thus, solve a problem wherein conventionally, since defrosting operation is performed only during operation, when the operation is stopped immediately before start of the defrosting operation, frost formation remains on an outdoor unit and shortage of capacity at restart of heating operation requires long time to blow out hot air.SOLUTION: This hot water heating device includes a defrosting operation control means. The defrosting operation control means starts defrosting operation of a heat pump cycle and stops a circulating pump, when compressor integrated operation time during heating operation exceeds a first predetermined time, outside air temperature sensed by an outside air temperature sensor is a first predetermined temperature or lower and a temperature difference between the outside air temperature and heat exchange temperature sensed by a defrosting sensor exceeds a second predetermined temperature; and finishes the defrosting operation and restarts the heating operation and operation of the circulating pump, when the temperature of the defrosting sensor exceeds a third predetermined temperature or when the compressor integrated operation time after start of the defrosting operation exceeds a second predetermined time. During stop of the operation, the defrosting operation control means starts the defrosting operation and continues the operation of the circulating pump, when the compressor integrated operation time exceeds the second predetermined time and when the outside air temperature is the first predetermined temperature or lower; and stops the entire operation when the temperature of the defrosting sensor exceeds the third predetermined temperature or after the compressor integrated operation time after start of the defrosting operation exceeds the second predetermined time.