AIR-CONDITIONER

PROBLEM TO BE SOLVED: To improve the efficiency of thermal recovery, by a method wherein a compressor, a heat-exchanger on the indoor side, a pressure reducing device, and a heat-exchanger on the indoor side are annually interconnected through a piping, and a heat recovery heat- exchanger paralleling the heat-exchanger on the outdoor side is connected to constitute a refrigerating cycle, and the heat recovery heat-exchanger is arranged in a ventilation passage to discharge indoor air to the outdoor. SOLUTION: After, during cooling operation, a refrigerant discharged from a compressor passes a four-way valve 12, the refrigerant is divided into two ways, Most of the refrigerant flows to a heat-exchanger 13 on the outdoor side and a part of the refrigerant flows to a heat recovery heat-exchanger 31 of a ventilation unit 30. After a refrigerant condensed by a heat-exchanger 13 on the outdoor side is reduced in a pressure in a pressure by a capillary tube 14, the refrigerant is vaporized by a heat-exchanger 21 on the indoor side and indoor air is cooled. Meanwhile, a refrigerant supplied to the heat recovery heat-exchanger 31 is heat-exchanged with indoor air decreased in temperature lower than the temperature of outside air. Thereafter, the refrigerant is returned to an outdoor machine 10a and after a pressure is reduced by a capillary tube 32, and supplied to the heat-exchanger 21 on the indoor side. This constitution maintains the interior of a house at a comfortable temperature as the efficiency of heat recovery is improved.