Abstract: An apparatus including a refrigerant circuit having a compressor, a heat source side heat exchanger and two or more heat exchangers related to heat medium. A heat medium circuit includes two heat medium loops each including a pump. A bypass piping is provided at the refrigerant circuit for bypassing the heart exchanger related to heat medium. A controller is configured to perform a defrosting operation, a heating operation, a heat recovery defrosting operation mode, and a bypass defrosting operation that melts frost attached to the heat source side heat exchanger during the heating operation mode by passing a portion or all of the heat source side refrigerant through the bypass piping.

Abstract: To obtain an air-conditioning apparatus that is capable of performing an effective defrosting operation, as well as saving energy, the air-conditioning apparatus has a heating operation mode that heats a heat medium in at least one of the heat exchangers related to heat medium, a heat recovery defrosting operation mode that melts frost attached to a heat source side heat exchanger—during the heating operation mode by operating at least one of the pumps and by making a heat source side refrigerant receive heat from the heat medium that is flowing in the at least one of the heat exchangers related to heat medium, and a bypass defrosting operation mode that melts frost attached to the heat source side heat exchanger during the heating operation mode by passing a portion or all of the heat source side refrigerant through a bypass piping.