Air-conditioning apparatus with multiple outdoor, indoor, and multiple relay units

An air-conditioning apparatus comprising:

• at least two outdoor units, each having a compressor, a first refrigerant flow path switching device and a heat source side heat exchanger;
• at least two heat medium relay units, each heat medium relay unit having, arranged in a refrigerant flow path, at least two second refrigerant flow path switching devices, at least two heat exchangers related to heat medium, a first opening/closing valve, a second opening/closing valve, expansion devices and at least two pumps;
• at least two indoor units, each having a use side heat exchanger;
• at least two flow path switching units having heat medium flow path switching devices;
• at least two refrigerating cycle systems arranged between each outdoor unit and a respective heat medium relay unit, each refrigerating cycle system respectively connecting the compressor for compressing a refrigerant, the refrigerant flow path switching device for switching the circulation path of the refrigerant, the heat source side heat exchanger for exchanging heat for the refrigerant, the expansion devices for adjusting the pressure of the refrigerant, and the heat exchangers related to heat medium which exchange heat between the refrigerant and the heat medium different from the refrigerant to be able to make the heat medium different in temperature respectively, by piping so as to constitute refrigerant circuits;
• and
• at least two heat medium side systems each respectively connecting the at least two pumps for circulating the heat medium for the at least two heat exchangers related to heat medium, the use side heat exchangers for exchanging heat between the heat medium and air of an air-conditioning target space and the heat medium flow switching devices for switching the heat medium which has passed through the at least two heat exchangers related to heat medium to the use side heat exchangers, by piping so as to constitute a heat medium circulation circuit, wherein
• the heat medium circulation circuit is constituted such that each of the use side heat exchangers in the at least two indoor units is capable of communicating with each of the heat exchangers related to heat medium constituting the at least two refrigerating cycle systems, and
• the air-conditioning apparatus further comprises a controller configured to, based on total values of each cooling capacity and heating capacity, the cooling capacity and the heating capacity each being necessary to the heat medium for a load related to each heat exchange of the use side heat exchangers, determine the number of compressors needed for supplying the totalized cooling capacity and the totalized heating capacity when the compressors operate with the maximum operation efficiency, and operate the determined number of the refrigerating cycle systems.