Patent ID: 7603872

Claim:
A heat-pump hot water supplying apparatus, comprising: a heat-pump circuit connecting a compressor, a water/refrigerant heat exchanger for conducting heat exchange between the refrigerant compressed in said compressor and water, a refrigerant adjusting device for decompressing of the refrigerant through open/close of a flow passage of the refrigerant after conducting heat exchange with the water and closing the flow passage when said compressor stops operation thereof, and an evaporator for conducting heat exchange between the refrigerant decompressed and an air, in series, through refrigerant pipes, respectively; and a hot water supplying circuit having a water supply pipe for supplying water into said water/refrigerant heat exchanger, and a hot water supplying pipe for supplying the water heated within said water/refrigerant heat exchanger; wherein said refrigerant adjusting device opens the flow passage of the refrigerant when said compressor starts the operation thereof; wherein an order is changed between start of operation of said compressor and opening of the refrigerant flow passage of said refrigerant adjusting device, depending upon pressure difference between discharge side pressure and suction side pressure of said compressor, when said compressor starts the operation thereof; wherein said compressor starts the operation thereof after the refrigerant flow passage of said refrigerant adjusting device opens, when the pressure difference is equal or greater than a predetermined value between the discharge side pressure and the suction side pressure of said compressor.