An air conditioning apparatus comprising: an outdoor unit for circulating refrigerant therethrough; at least one indoor unit (61, 62, 63, 64) for circulating water therethrough; and a heat exchange device connected to the indoor unit (61, 62, 63, 64) and to the outdoor unit for performing heat exchange between the refrigerant and the water; connection pipes (20, 25, 27) for connecting the outdoor unit to the heat exchanger device, wherein the connection pipes (20, 25, 27) comprise a first outdoor unit connection pipe for high-pressure gas refrigerant, a second outdoor unit connection pipe for low-pressure gas refrigerant, and a third outdoor unit connection pipe for liquid refrigerant, wherein the first outdoor unit connection pipe, the second outdoor unit connection pipe, and the third outdoor unit connection pipe are respectively connected to the outdoor unit; and a control unit configured to control at least one of the outdoor unit, the indoor unit (61, 62, 63, 64) and operation of the heat exchange device; wherein the heat exchange device comprises: a first heat exchanger and a second heat exchanger, each being connected to a first refrigerant pipe (111a, 111b) and a second refrigerant pipe (121, 122), respectively; a branch pipe connected to the first outdoor unit connection pipe; a branch pipe connected to the second outdoor unit connection pipe; and a common gas pipe connecting the branch pipes (101a, 103a) to each other, wherein the common gas pipe is connected to the first refrigerant pipes (111a, 111b); a first and second expansion valve (125, 126) respectively provided in the second refrigerant pipe connected to the first heat exchanger and in the second refrigerant pipe connected to the second heat exchanger; a bypass pipe connecting the second refrigerant pipe connected to the first heat exchanger and the first refrigerant pipe connected to the second heat exchanger; and a bypass valve provided in the bypass pipe, wherein the third outdoor unit connection pipe is connected to the second refrigerant pipes (121, 122). an outdoor unit for circulating refrigerant therethrough; at least one indoor unit (61, 62, 63, 64) for circulating water therethrough; and a heat exchange device connected to the indoor unit (61, 62, 63, 64) and to the outdoor unit for performing heat exchange between the refrigerant and the water; connection pipes (20, 25, 27) for connecting the outdoor unit to the heat exchanger device, wherein the connection pipes (20, 25, 27) comprise a first outdoor unit connection pipe for high-pressure gas refrigerant, a second outdoor unit connection pipe for low-pressure gas refrigerant, and a third outdoor unit connection pipe for liquid refrigerant, wherein the first outdoor unit connection pipe, the second outdoor unit connection pipe, and the third outdoor unit connection pipe are respectively connected to the outdoor unit; and a control unit configured to control at least one of the outdoor unit, the indoor unit (61, 62, 63, 64) and operation of the heat exchange device; wherein the heat exchange device comprises: a first heat exchanger and a second heat exchanger, each being connected to a first refrigerant pipe (111a, 111b) and a second refrigerant pipe (121, 122), respectively; a branch pipe connected to the first outdoor unit connection pipe; a branch pipe connected to the second outdoor unit connection pipe; and a common gas pipe connecting the branch pipes (101a, 103a) to each other, wherein the common gas pipe is connected to the first refrigerant pipes (111a, 111b); a first and second expansion valve (125, 126) respectively provided in the second refrigerant pipe connected to the first heat exchanger and in the second refrigerant pipe connected to the second heat exchanger; a bypass pipe connecting the second refrigerant pipe connected to the first heat exchanger and the first refrigerant pipe connected to the second heat exchanger; and a bypass valve provided in the bypass pipe, wherein the third outdoor unit connection pipe is connected to the second refrigerant pipes (121, 122). a first heat exchanger and a second heat exchanger, each being connected to a first refrigerant pipe (111a, 111b) and a second refrigerant pipe (121, 122), respectively; a branch pipe connected to the first outdoor unit connection pipe; a branch pipe connected to the second outdoor unit connection pipe; and a common gas pipe connecting the branch pipes (101a, 103a) to each other, wherein the common gas pipe is connected to the first refrigerant pipes (111a, 111b); a first and second expansion valve (125, 126) respectively provided in the second refrigerant pipe connected to the first heat exchanger and in the second refrigerant pipe connected to the second heat exchanger; a bypass pipe connecting the second refrigerant pipe connected to the first heat exchanger and the first refrigerant pipe connected to the second heat exchanger; and a bypass valve provided in the bypass pipe, wherein the third outdoor unit connection pipe is connected to the second refrigerant pipes (121, 122).