A refrigeration cycle apparatus includes a compressor, a first heat exchanger, a decompressing device, a second heat exchanger, a first switching valve, a second switching valve, and a controller. The first switching valve is switched to one of a first state and a second state. The second switching valve is switched to one of a third state, a fourth state, and a fifth state. When switching to a second cooling operation to bring the first and second switching valves into the second and fourth states respectively, is requested during a first cooling operation to bring the first and second switching valves into the first and third states, respectively, the controller performs a first switching operation to bring the first switching valve into the second state and bring the second switching valve into the fifth state, and thereafter switches the first switching operation to the second cooling operation.

An additive heat transfer unit (AHTU) can be part of or added to an air source heat pump HVAC system. The heat pump system can include a compressor, an expansion valve, first and second air source heat exchangers, and a reversing valve. The system can have a cooling mode and a heating mode, such that in the cooling mode the first air source heat exchanger functions as an evaporator and the second air source heat exchanger functions as a condenser, this being reversed in the heating mode. The AHTU can include a liquid source heat exchanger that can be used to increase the efficiency of the system.

An air-conditioning apparatus includes a primary-side circuit in which a compressor, a first flow switching device, an outdoor heat exchanger, a second flow switching device, a first expansion device, and a relay heat exchanger are connected by pipes and in which refrigerant circulates; a secondary-side circuit in which the relay heat exchanger, a pump, a plurality of indoor heat exchangers, and heat medium flow control devices are connected by pipes and in which a heat medium circulates; and a controller configured to control the first and second flow switching devices such that in cooling and heating operations, the refrigerant and a heat-source-side fluid flow through the outdoor heat exchanger in opposite directions and the refrigerant flows through the relay heat exchanger in a constant direction. The pump is installed such that the heat medium, the refrigerant flow, and air for an air-conditioning target space flow in particular directions.

An air conditioner may include a plurality of indoor units and a plurality of outdoor units connected to the plurality of indoor units. Each of the plurality of outdoor units may include a plurality of outdoor heat exchangers. Each of the outdoor heat exchangers may include a plurality of heat exchanger parts. When a defrosting operation condition is satisfied during a heating operation, indicating that a defrosting operation should be performed the plurality of heat exchanger parts of the plurality of outdoor heat exchangers may successively perform the defrosting operation.

A multi-split air-conditioner and an outdoor unit system thereof are provided. The outdoor unit system includes: a compressor (1) having a gas outlet (a) and a gas inlet (b); an outdoor heat exchanger (2) having an inlet (c) and an outlet (d); a switching assembly (3) having first to sixth ports, wherein the first port (e) is connected with the gas outlet (a) of the compressor (1), the second port (f) is connected with the gas inlet (b) of the compressor (1), the third port (g) is connected with the inlet (c) of the outdoor heat exchanger (2), the fourth port (h) is connected with the outlet (d) of the outdoor heat exchanger (2), the fifth port (i) is connected with an inlet pipe (4) and the sixth port (j) is connected with an outlet pipe (5).

A multi-type air conditioner may include three pipes, including a high-pressure pipe, a low-pressure pipe, and a liquid line which may be connected to a plurality of indoor units, in which some of the indoor units may be operated in a cooling mode and the rest of the indoor units may be operated in a heating mode, such that waste heat from the indoor units operated in the heating mode may be recovered to be used for the indoor units operated in the cooling mode.

An HVAC system includes an outdoor heat exchanger. A first indoor heat exchanger is fluidly coupled to the outdoor heat exchanger and disposed in a first zone. A second indoor heat exchanger is fluidly coupled to the outdoor heat exchanger and disposed in a second zone. A compressor is fluidly coupled to the outdoor heat exchanger, the first indoor heat exchanger, and the second indoor heat exchanger. A first circulation fan is positioned to circulate air around the first indoor heat exchanger and a second circulation fan is positioned to circulate air around the second indoor heat exchanger. A first zone controller is electrically coupled to the first indoor heat exchanger. The first zone controller is configured to measure a temperature in the first zone, compare the measured temperature to a setpoint temperature of the first zone, and responsive to a difference between the measured temperature and the setpoint temperature, adjust a speed of the first circulation fan independent of the speed of the second circulation fan.

An air-conditioning apparatus that can prevent freezing of a heat transfer medium even when using a non-azeotropic refrigerant mixture. The air-conditioning apparatus is designed such that when a heat exchanger serves as a cooler that cools a heat transfer medium, it controls a heat medium passage reversing device. This is so that, when a heat transfer medium flowing through a heat medium flow passage will not be frozen, a refrigerant flowing through a refrigerant flow passage and the heat transfer medium flowing through the heat medium flow passage are in counter flow. It is also to control the heat medium passage reversing device so that, when there is a possibility of freezing the heat transfer medium flowing through the heat medium flow passage, the refrigerant flowing through the refrigerant flow passage and the heat transfer medium flowing through the heat medium flow passage are in parallel flow.

The present disclosure provides a heat pump system and a control method. The heat pump system includes a compressor, a first flow path, a second flow path and a third flow path. The second end of the first flow path, the second end of the second flow path and the second end of the third flow path are connected. Two of the first end of the first flow path, the first end of the second flow path and the first end of the third flow path are connected to the inlet and outlet of the compressor in specific modes through a switching assembly so that the heat pump system can operate in one or more of a cooling mode, a heating mode, a hot water preparing mode and a cooling heat recovery mode.

A heat-pump system may include a compressor, an outdoor heating exchanger, an indoor heat exchanger, an expansion device, and a supplemental heater. The outdoor heat exchanger may be in fluid communication with the compressor. The indoor heat exchanger may be in fluid communication with the compressor. The expansion device may be in fluid communication with the indoor and outdoor heat exchangers. The supplemental heater may include a burner and a working-fluid conduit. The burner may be configured to burn a fuel and heat the working-fluid conduit. When the heat-pump system is operating in a heating mode, the indoor heat exchanger may receive working fluid from the working-fluid conduit such that the working fluid flows from an outlet of the working-fluid conduit to an inlet of the indoor heat exchanger.