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.

A defrosting control method of a multi-functional multi-split system with double four-way valves. The multi-functional multi-split system includes an outdoor unit, at least one set of hydraulic modules, and at least one set of indoor modules. When the multi-split system is switched from a normal operation mode to a defrosting mode, a first four-way valve and a second four-way valve are powered down, and operation modes of each set of indoor modules and each set of hydraulic modules, the on/off state of fans of an indoor heat exchanger and a hydraulic heat exchanger, opening degrees of a first electromagnetic valve of the indoor heat exchanger and a second electromagnetic valve of the hydraulic heat exchanger, and the on/off state of the first electromagnetic valve and the second electromagnetic valve are correspondingly adjusted based on the previous operation modes of each set of indoor modules and each set of hydraulic modules.

An air conditioning, heat pump and water heating system includes a compressor, a switching valve, an outdoor heat exchanger, a refrigerant storage tank, an indoor heat exchanger and a water heater. The air conditioning, heat pump and water heating system is configured to selectively operate between an air conditioning mode, a heat pump mode, a first water heating mode and a second water heating mode. In the first water heating mode, heat absorbed from an indoor space is utilized to heat up water circulating in the water heater so that when the air conditioning, heat pump and water heating system is operated in the first water heating mode, no heat is discharged to ambient environment. In the second water heating mode, heat absorbed from an ambient environment is utilized to heat up water circulating in the water heater.

A heat pump system comprises a compressor, a first heat exchanger, a second heat exchanger, a mode switching valve, a throttling element and a reservoir, wherein the throttling element is arranged on a flow path between the first heat exchanger and the second heat exchanger; and which further comprises a mode switching flow path in which a first flow path and a second flow path are arranged, the reservoir is arranged on the second flow path and each flow path is controllably opened or closed to realize different functional modes.

An air-conditioning apparatus includes an outdoor heat exchanger. The outdoor heat exchanger includes a first heat exchanger and a second heat exchanger. A controller performs a heating operation and a heating-defrosting operation, in which one of the first heat exchanger and the second heat exchanger functions as an evaporator, an other one the first heat exchanger and the second heat exchanger functions as a condenser. When a temperature of the indoor heat exchanger by a temperature detection unit is treated as a first temperature, and a temperature of the indoor heat exchanger by the temperature detection unit is treated as a second temperature, the controller reduces a rotation speed of an indoor fan in a case where the second temperature is lower than the first temperature and where a difference between the first temperature and the second temperature is greater than or equal to a first setting value.

An air conditioning system includes a bypass passage and a cooling-heating switching mechanism. The bypass passage is configured to be at least a part of a flow passage connecting a third port to a refrigerant inlet of a compressor. A second expansion valve opens and closes the bypass passage. The cooling-heating switching mechanism includes check valves and four-way valves. The four-way valve causes a refrigerant outlet of the check valve to communicate with one of the refrigerant inlet and a refrigerant outlet of the compressor. The four-way valve causes a refrigerant inlet of the check valve to communicate with one of the refrigerant inlet and the refrigerant outlet of the compressor and causes a port to communicate with the other of the refrigerant inlet and the refrigerant outlet.

An air conditioner unit includes a compressor, an exterior coil, a main interior coil, a main expansion device, a reheat interior coil and a reheat expansion device. The reheat interior coil is positioned adjacent the main interior coil. The main expansion device is connected in series between the exterior coil and the main interior coil, and the reheat expansion device is connected in series between the main expansion device and the reheat interior coil. A reheat valve is operable to selectively adjust a flow direction through the reheat interior coil. The reheat valve is a four-way valve, and one port of the four-way valve is blocked.

An air conditioner includes a refrigeration cycle in which a first compressor and a second compressor are connected in parallel, and the first compressor, the second compressor, a first outdoor heat exchanger, a second outdoor heat exchanger, a first indoor heat exchanger, a second indoor heat exchanger, and expansion valves are connected. When the air conditioning apparatus is operated in a first operation mode in which the second outdoor heat exchanger and the first indoor heat exchanger are operated as condensers and the second indoor heat exchanger is operated as an evaporator, refrigerant discharged from the first compressor flows through the first indoor heat exchanger, the expansion valves, and the second indoor heat exchanger in order while bypassing the first outdoor heat exchanger and the second outdoor heat exchanger.

The air conditioner has a configuration such that, in an air-warming operation: the average refrigerant exit temperature, which is obtained by averaging the temperature of the refrigerant exits of indoor heat exchangers 7 in a plurality of indoor units 10, as detected by heat-exchanger-refrigerant-exit temperature probes 34 in the indoor units 10, is determined; the temperature difference between the average refrigerant exit temperature and the refrigerant exit temperatures of the indoor heat exchangers 7 of each of the indoor units 10 is determined; and the degree to which indoor expansion valves 9 of the indoor units 10 are open is controlled such that the determined temperature difference falls within a predetermined temperature difference range.

A heat source unit includes a first switching valve configured to switch between a first state where the first switching valve brings a high and low pressure gas connection pipe and a discharge side of a compressor into communication with each other and a second state where the first switching valve brings the high and low pressure gas connection pipe and a suction side of the compressor into communication with each other; and a second switching valve configured to switch between a third state where while the second switching valve brings the discharge side of the compressor and a gas end of a first heat exchange section into communication with each other, the second switching valve brings the suction side of the compressor and a gas end of the second heat exchange section into communication with each other and a fourth state where while the second switching valve brings the discharge side of the compressor and the gas end of the second heat exchange section into communication with each other, the second switching valve brings the suction side of the compressor and the gas end of the first heat exchange section into communication with each other.