Abstract: A refrigerant pipe unit for a room air-conditioner includes two refrigerant pipes laid through a piping hole in the building wall and interconnecting an indoor unit and an outdoor unit of the room air-conditioner for circulation of a refrigerant through the room air-conditioner. A stop valve is attached to at least one end of each of the refrigerant pipes for blocking flow of the refrigerant between the indoor unit and the outdoor unit. A maximum size of the stop valve which is measured in a radial direction about the central axis of each refrigerant pipe is designed such that the stop valve attached to the end of each refrigerant pipe can pass through the piping hole while the other refrigerant pipe is present inside the piping hole. Thus, the air-conditioner can be disassembled while the refrigerant is kept sealed within the indoor unit, the outdoor unit and the refrigerant pipe unit.

Abstract: In order to seal in refrigerant in a heat exchanger as much quantity as possible till to reuse the refrigerant at a new place of the heat exchanger after transfer or till to recover the refrigerant at a refrigerant recovery site, even when electricity is suspended to the new place or when outside temperature is lower than a certain temperature at the place where the heat exchanger such as an air conditioner having a separated interior instrument and exterior instrument is being installed, two on-off valves are provided in the refrigerant piping of the interior instrument besides two on-off valves provided in the refrigerant piping of the exterior instrument, or on-off valves are provided in each connecting pipe connecting with the refrigerant piping of the interior instrument and the refrigerant piping of the exterior piping, and the refrigerant is sealed in by closing all the on-off valves.