To solve the problem that a conventional absorption refrigerating machine (a small-size machine, generally) requires a boosting pump used to send a low-density solution from an absorber to a generator (via a rectifier part sometimes), however, the pump has a small flow rate and high lift whereby the construction of the pump becomes special in case of a small-size machine.

The solution is sent to the generator (via the rectifier sometimes) by employing a pressure vessel, a check valve, a solenoid valve, a regulating valve or the like without employing any solution pump. Further, circulating liquid can be sent by the pressure vessel without employing any pump in such a construction that the circulating liquid (high-pressure refrigerant, reflux liquid) is sent to the upper part of the rectifier.