A refrigerating cycle device includes a compressor, a motor, and a wiring switch part. The compressor compresses a refrigerant. The motor generates power for compressing the refrigerant by rotating a rotor with voltage applied to a plurality of wirings. The motor is disposed in the compressor. The wiring switch part switches between a plurality of wiring states by changing connection between the plurality of wirings. When a rotational speed of the rotor exceeds a predetermined value, the wiring switch part switches to a first wiring state of the plurality of wiring states. The first wiring state differs from a second wiring state of the plurality of wiring state. Efficiency of the second wiring state is highest at the rotational speed.

A method of mitigating liquid-refrigerant migration includes comparing a requested compressor speed of a variable-speed compressor to a pre-defined threshold and, responsive to a determination that the requested compressor speed is greater than the pre-defined threshold, operating the variable-speed compressor at a first compressor speed that is less than the requested compressor speed.

The refrigeration cycle apparatus includes a refrigerant circuit, a controller to control the refrigerant circuit, a bypass flow path, and a flow control valve. The bypass flow path communicates between the discharge side of the compressor and the first outdoor heat exchanger or between the discharge side of the compressor and the second outdoor heat exchanger. The flow control valve is provided to the bypass flow path. The refrigerant circuit is configured to be able to perform a heating defrosting simultaneous operation. The heating defrosting simultaneous operation is an operation of supplying part of the refrigerant discharged from the compressor to one of the first outdoor heat exchanger and the second outdoor heat exchanger via the bypass flow path, causing the other of the first outdoor heat exchanger and the second outdoor heat exchanger to serve as an evaporator, and causing the indoor heat exchanger to serve as a condenser.

A heat pump is provided that includes a first pipe in which a first refrigerant flows; a second pipe disposed at a side of the first pipe and in which a second refrigerant flows; a first heat exchanger connected with the first pipe and the second pipe and in which the first refrigerant exchanges heat with the second refrigerant; a boiler connected with the first pipe and in which the first refrigerant flows; a compressor connected with the second pipe and that compresses the second refrigerant; a second heat exchanger connected with the second pipe and in which the second refrigerant exchanges heat with outdoor air; a bypass pipe branched from first pipe and configured to exchange heat with the second heat exchanger; and a three-way valve that directs the first refrigerant to pass through the bypass pipe. When the outdoor heat exchanger operates as an evaporator, frost formation thereon may be prevented.

In a split system heat pump cooling and heating system, an auxiliary hot water storage tank is provided as an energy storage bank. Two sets of coils run through this storage tank, a first set carrying hot refrigerant from the heat pump to deposit energy and a second set carrying hot potable water to remove energy. Valve and switch matrixes are operated at the heat pump to provide hot potable water from the energy storage bank during both normal space heating and cooling operations of the heat pump.

An air conditioner and a control method thereof. The air conditioner includes an indoor unit including an indoor heat exchanger and an indoor fan, an outdoor unit connected to the indoor unit and including an outdoor heat exchanger, an outdoor fan, a compressor, an expansion valve, and a four-way valve, and at least one processor configured to perform a test operation by controlling the indoor unit and the outdoor unit. Based on an outdoor temperature being less than a predetermined reference temperature, the at least one processor is configured to determine whether the indoor unit and the outdoor unit operate normally, by continuously performing a heating operation and a defrosting operation during the test operation.

The present disclosure relates to a heat pump system comprising an outdoor unit disposed in an outdoor space, a plurality of thermal load units supplied with cool air and hot air, and an intermediate unit disposed between the outdoor unit and the plurality of thermal load units, wherein the intermediate unit is connected to the outdoor unit through refrigerant pipes and connected to the plurality of thermal load units through thermal medium pipes.

A defrost method for a heat pump system includes running the heat pump system in a heating mode to provide heat to an enclosed space and determining if an outdoor temperature is less than an outdoor threshold temperature. Responsive to a determination that the outdoor temperature is below the outdoor threshold temperature, determining if a calibration state has been previously run. Responsive to a determination that the calibration state has not been previously run, running the heat pump system in the calibration state. Responsive to a determination that the calibration state has been previously run, determining if a temperature difference between a temperature of an evaporator coil of the heat pump system and the outdoor temperature exceeds a temperature threshold value. Responsive to a determination that the temperature difference between the evaporator coil and the outdoor temperature is greater than the temperature threshold value, running the heat pump system in a defrost state.

An air conditioner includes an outdoor unit in which a refrigerant circulates; an indoor unit in which water circulates; a heat exchange device including a heat exchanger that connects the outdoor unit to the indoor unit and performs heat exchange between the refrigerant and the water; a first outdoor unit connection pipe configured to connect the outdoor unit and the heat exchange device, a high-pressure gaseous refrigerant flowing in the first outdoor unit connection pipe; a second outdoor unit connection pipe configured to connect the outdoor unit and the heat exchange device, a low-pressure gaseous refrigerant flowing in the second outdoor unit connection pipe; a third outdoor unit connection pipe configured to connect the outdoor unit and the heat exchange device, a liquid refrigerant lowing in the third outdoor unit connection pipe; a bypass pipe configured to communicate the third outdoor unit connection pipe and the second outdoor unit connection pipe; and a bypass valve provided in the bypass pipe.

The disclosed technology includes systems and methods of reducing frost accumulation on a heat pump evaporator coil. The disclosed technology can include a heat pump assembly having an evaporator coil, a fan configured to direct air across the evaporator coil, a temperature sensor, and a controller configured to energize the fan to direct air across the evaporator coil when the temperature of the evaporator coil is below a threshold temperature.