Abstract: Provided is a main refrigerant circuit in which a compressor having an injection port, a condenser, a main circuit expansion device unit, and an evaporator are connected by pipes to allow refrigerant to circulate in the main refrigerant circuit; an injection pipe an injection expansion device; an outside-air temperature detection device; a suction pressure detection device; and a controller, wherein the main circuit expansion device unit includes a plurality of main circuit expansion devices with different capacities and in a parallel-connected relationship, and during operation, when the controller determines that the temperature of the outside air is equal to or lower than a set temperature, the controller is configured to open the injection expansion device to control an opening degree to select the main circuit expansion device based on the suction pressure to control an opening degree of the selected main circuit expansion device.

Abstract: A heat-pump water heater includes a refrigerant circuit, a water circuit, and a controller. The refrigerant circuit includes a main circuit and a bypass circuit. The main circuit includes a compressor, a water heat exchanger, a first pressure-reducing device, an air heat exchanger, and an air-sending device. The bypass circuit includes a second pressure-reducing device. The water circuit includes a hot water tank, a water pump, and the water heater exchanger. In a night-time hot-water supply mode, the controller causes the water pump with a lowest frequency set in advance, causes the compressor with a lowest frequency set in advance, and stops the air-sending device.