To provide a heat pump water heater that improves heat exchange efficiency between a refrigerant and water in a water-refrigerant heat exchanger in starting to boil up, and can improve COP in starting to boil up.
A heat pump water heater includes: a refrigerant circuit 5; a circulator pump 8 that circulates hot water in a hot water supply circuit 10; a tapping temperature detection means 11 that detects the temperature of the hot water heated in the water-refrigerant heat exchanger 2; and a control means 14. In boiling-up operation that heats hot water in the water-refrigerant heat exchanger 2, the number of rotation of the circulator pump 8 when temperature detected by the tapping temperature detection means 11 is almost stable is stored in the control means 14 and regarded as a target rotation number the next time the boiling-up operation is started, wherein the COP can be improved at start of boiling-up operation.
YAMAOKA YOSHIKI
HAMADA MASAYUKI
Daisuke Nagano
Kentaro Fujii