To provide a heat pump water heater capable of optimizing energy consumption efficiency while accurately controlling a tapping temperature.
From a target value table, a target temperature difference, between a discharge temperature and a condensation temperature, is decided which corresponds to set the tapping temperature, a detected incurrent temperature, and a detected external air temperature, and at which COP is maximized (S1). The rotation speed of the compressor is controlled and changed so that the detected condensation temperature will reach the target condensation temperature (S4). At that occasion, a temperature difference between the detected discharge temperature and the detected condensation temperature of a refrigerant discharged from the compressor 11 is computed, and the opening of an expansion valve 13 is controlled and changed so that a value of the temperature difference will reach the target temperature difference (S5).
FUJII HIRONOBU
OTOMO ICHIRO
| JP2004340535A | 2004-12-02 | |||
| JP2009186121A | 2009-08-20 | |||
| JP2010048518A | 2010-03-04 |
Taro Murakami