Air conditioner construction method

A reinstallation method for upgrading an air conditioner including a refrigerant circuit that comprises an outdoor unit and a plurality of indoor units to perform a cooling/heating switchable refrigeration cycle into an air conditioner including a refrigerant circuit that is able to perform a refrigeration cycle in which a cooling operation and a heating operation are performed in parallel with each other, the reinstallation method comprising:

• an operation switching unit connecting step to connect each of the operation switching units, which changes directions of a refrigerant flowing through its associated indoor unit in response to a switch from a cooling operation to a heating operation, or vice versa, with the associated indoor unit through two indoor communication pipes that form parts of preinstalled communication piping;
• a gas-liquid separation unit connecting step to connect the gas-liquid separation unit, which is disposed separately from the operation switching units and includes a gas-liquid separator and a refrigerant flow channel switching circuit that switches flows of a liquid refrigerant and a gas refrigerant, with the outdoor unit through two outdoor communication pipes that form other parts of the preinstalled communication piping;
• and
• a pipe connecting step to connect the operation switching units with the gas-liquid separation unit in parallel with each other through two intermediate communication pipes that form still other parts of the preinstalled communication piping and one intermediate communication pipe newly installed.