A collective unit for switching refrigerant flow arranged between an indoor unit and an outdoor unit , comprising: multiple high-pressure valves ; multiple low-pressure valves ; a high-pressure header ; a low-pressure header ; a high-pressure gas pipe connecting each high-pressure valve and the high-pressure header ; and a low-pressure gas pipe connecting each low-pressure valve and the low-pressure header , wherein the multiple high-pressure valves are arranged next to each other in a first direction perpendicular to a vertical direction, the multiple low-pressure valves are arranged next to each other in the first direction, and the low-pressure valves , the low-pressure header , and the low-pressure gas pipe are arranged on one side in a second direction perpendicular to the vertical direction and the first direction with respect to the high-pressure valves , the high-pressure header , and the high-pressure gas pipe , the collective unit further comprising: a connection gas pipe connecting each high-pressure valve and each low-pressure valve , wherein the high-pressure valves , the high-pressure header , and the high-pressure gas pipe are arranged on the other side in the second direction with respect to the connection gas pipe , and the low-pressure valves , the low-pressure header , and the low-pressure gas pipe are arranged on the one side in the second direction with respect to the connection gas pipe . multiple high-pressure valves ; multiple low-pressure valves ; a high-pressure header ; a low-pressure header ; a high-pressure gas pipe connecting each high-pressure valve and the high-pressure header ; and a low-pressure gas pipe connecting each low-pressure valve and the low-pressure header , wherein the multiple high-pressure valves are arranged next to each other in a first direction perpendicular to a vertical direction, the multiple low-pressure valves are arranged next to each other in the first direction, and the low-pressure valves , the low-pressure header , and the low-pressure gas pipe are arranged on one side in a second direction perpendicular to the vertical direction and the first direction with respect to the high-pressure valves , the high-pressure header , and the high-pressure gas pipe , the collective unit further comprising: a connection gas pipe connecting each high-pressure valve and each low-pressure valve , wherein the high-pressure valves , the high-pressure header , and the high-pressure gas pipe are arranged on the other side in the second direction with respect to the connection gas pipe , and the low-pressure valves , the low-pressure header , and the low-pressure gas pipe are arranged on the one side in the second direction with respect to the connection gas pipe . a connection gas pipe connecting each high-pressure valve and each low-pressure valve , wherein the high-pressure valves , the high-pressure header , and the high-pressure gas pipe are arranged on the other side in the second direction with respect to the connection gas pipe , and the low-pressure valves , the low-pressure header , and the low-pressure gas pipe are arranged on the one side in the second direction with respect to the connection gas pipe . <EOS>