Abstract: A heat-pump refrigeration cycle is constructed using a compressor, a four-way valve, a water heat exchanger, a receiver, and air heat exchangers. The compressor draws in, compresses, and discharges refrigerant. The four-way valve switches a direction of refrigerant flow, and a water heat exchanger allows an exchange of heat between inflow refrigerant and water supplied from a water supply unit. The receiver stores liquefied refrigerant, and a parallel circuit of a plurality of air heat exchangers allows an exchange of heat between the inflow refrigerant and indoor air. The water heat exchangers are positioned at a location higher than the receiver, which, during the cooling operation, permits liquefied refrigerant generated at the water heat exchanger to run down into the receiver. This prevents the refrigerant from remaining in the water heat exchangers.

Abstract: An air conditioner includes a first refrigeration cycle with a capacity-variable type compressor, and a second refrigeration cycle with a constant rotation type compressor, both refrigeration cycles having outdoor heat exchangers while utilizing a single common indoor heat exchanger. The first refrigeration cycle has a bypass passage connected, at one end, between the suction side of the compressor and the indoor heat exchanger, and, at the other end, between the indoor heat exchanger and the outdoor heat exchanger. When the second refrigeration cycle is stopped, or the capacity variable compressor operated at a low operation frequency, a part of the coolant which passes through the outdoor heat exchanger in the first refrigeration cycle flows into the suction side of the compressor through the bypass passage.