Air-conditioning apparatus with relay unit

An air-conditioning apparatus comprising:

• a compressor;
• a heat source side heat exchanger;
• a plurality of expansion devices;
• a plurality of heat exchangers related to a heat medium;
• a plurality of pumps;
• and a plurality of use side heat exchangers,
• the compressor, the heat source side heat exchanger, the expansion devices, and the heat exchangers related to the heat medium being connected to form a refrigerant circuit in which a heat-source-side refrigerant is circulated,
• the pumps, the use side heat exchangers, and the heat exchangers related to the heat medium being connected to form a heat medium circuit in which the heat medium is circulated,
• the air-conditioning apparatus being capable of carrying out a cooling and heating mixed operation mode in which a high-temperature high-pressure heat-source-side refrigerant discharged from the compressor flows into at least one of the heat exchangers related to the heat medium to heat the heat medium and a low-temperature low-pressure heat-source-side refrigerant flows into at least another one of the heat exchangers related to the heat medium to cool the heat medium, a heating-only operation mode in which a high-temperature high-pressure heat-source-side refrigerant discharged from the compressor flows into each of the heat exchangers related to the heat medium to heat the heat medium, and a cooling-only operation mode in which a low-temperature low-pressure heat-source-side refrigerant flows into each of the heat exchangers related to the heat medium to cool the heat medium,
• wherein
• the air-conditioning apparatus is configured such that all of the heat-source-side refrigerant that is discharged from the compressor flows into all of the heat exchangers related to the heat medium in series in the cooling and heating mixed operation mode and such that the heat-source-side refrigerant that is discharged from the compressor flows into all of the heat exchangers related to the heat medium in parallel and joins together after passing through each of the heat exchangers related to the heat medium in the heating only operation mode.