A heat pump system, a controlling method thereof, and a heat pump unit using the heat pump system. The heat pump system includes a compressor, a first heat exchanger, a second heat exchanger, a heat-recovery-type heat exchanger, a multi-way valve, a throttling element, and a mode-switching flow path, which has both air conditioning and water heating functions. By switching the multi-way valve and powering on/off electromagnetic valves in the heat pump system, the controlling method controls the heat pump system to implement multiple functional modes. Furthermore, the heat pump unit using the heat pump system provides multiple functions simply by laying a small amount of parts and elements and pipelines outdoors, thereby greatly reducing the engineering cost and cost of parts, and ensuring a much higher water heating efficiency.

A refrigeration cycle apparatus includes a heat exchanger, and a flow switching circuit configured to switch the heat exchanger to act as any one of an evaporator and a condenser, the flow switching circuit is configured to allow refrigerant to flow into the heat exchanger in the same direction both in a case where the heat exchanger acts as an evaporator and in a case where the heat exchanger acts as a condenser, the heat exchanger includes a path switching circuit including a plurality of paths, and the path switching circuit is configured to switch an order of the plurality of paths through which refrigerant flows between an order of the plurality of paths in the case where the heat exchanger acts as an evaporator and another order of the plurality of paths in the case where the heat exchanger acts as a condenser.

Operation switching units, each changing directions of a refrigerant flowing through its associated indoor unit in response to a switch from a cooling operation to a heating operation, or vice versa, are each connected with the associated indoor unit through indoor communication pipes; a gas-liquid separation unit is connected with an outdoor unit through outdoor communication pipes; and the operation switching units are connected with the gas-liquid separation unit through two intermediate communication pipes preinstalled and one intermediate communication pipe newly installed. This provides a simple and cost-effective means for upgrading a preinstalled air conditioner making a switch from cooling to heating, and vice versa, into an air conditioner that can perform a cooling operation and a heating operation in parallel with each other.

The air conditioner includes: an outdoor unit that includes a compressor, an outdoor heat exchanger, and an outdoor expansion valve; an indoor unit that includes an indoor heat exchanger and an indoor expansion valve; a liquid pipe that connects the outdoor unit to the indoor unit; and a gas pipe that connects the outdoor unit to the indoor unit. One end of the outdoor heat exchanger is coupled to the liquid pipe through the outdoor expansion valve. One end of the indoor heat exchanger is coupled to the liquid pipe through the indoor expansion valve. When a predetermined period of time elapses after the compressor is shut down, the outdoor expansion valve and the indoor expansion valve both close.

An air-conditioning apparatus includes a heat source unit, a plurality of indoor units, and a relay unit. The heat source unit includes a heat-source-side flow control valve connected to a heat-source-side heat exchanger, a bypass pipe connected in parallel to the heat-source-side heat exchanger, a bypass flow control valve provided in the bypass pipe, and a gas-liquid separating unit configured to, when refrigerant flows out to the high-pressure pipe, mix refrigerant in a liquid state flowing through the heat-source-side heat exchanger and refrigerant in a gas state flowing through the bypass pipe and cause mixed refrigerant to flow out to the high-pressure pipe, and configured to, when refrigerant flows in from the low-pressure pipe, separate the refrigerant flowing in from the low-pressure pipe into refrigerant in a liquid state flowing into the heat-source-side heat exchanger and refrigerant in a gas state flowing into the bypass pipe.

An air-conditioning apparatus includes at least one system including a heat-medium conveying device, a heat-medium flow regulator, and a heat-medium flow control device, as a heat medium system capable of regulating a flow rate of a heat medium supplied to a heat source device-side heat exchanger exchanging heat between refrigerant and the heat medium. The air-conditioning apparatus switches each of a plurality of use-side heat exchangers to a cooling operation or a heating operation in accordance with a control command to perform a cooling and heating simultaneous operation. The refrigerant is caused to flow through the heat source device-side heat exchanger depending on a ratio of a total cooling capacity and a total heating capacity of the plurality of use-side heat exchangers. The heat-medium flow control device controls the flow rate of the heat medium supplied to the heat source device-side heat exchanger based on a difference between the total cooling capacity and the total heating capacity of the plurality of use-side heat exchangers and a total operation capacity of the heat source device-side heat exchanger.

An object is to provide a refrigeration cycle apparatus that does not cause unevenness of capacity among branch units and a failure in controlling a refrigerant circuit. At least one of branch units is a first branch unit having a minimum pressure loss in distribution of refrigerant in a high-pressure refrigerant pipe between a heat source unit and the branch units, and at least another one of the branch units is a second branch unit having a maximum pressure loss in distribution of refrigerant in the high-pressure refrigerant pipe between the heat source unit and the branch units. An opening degree of an expansion device is controlled in such a manner that a differential pressure between a refrigerant pressure detected by a high-pressure detecting device of the first branch unit and a refrigerant pressure detected by an intermediate-pressure detecting device is greater than or equal to a set value PHM.

An air-conditioning apparatus includes a refrigerant circuit connecting a compressor, a first heat exchanger, a first expansion device, and a second heat exchanger. The compressor and the first heat exchanger are housed in a heat source unit, the heat source unit, houses a second expansion device provided at a location on a downstream side with respect to the first heat exchanger and on an upstream side with respect to the first expansion device, and the second expansion device and the first expansion device are connected via an extension pipe. The second expansion device reduces a pressure of refrigerant flowing into the extension pipe in cooling operation to cause the refrigerant to turn into refrigerant having a medium pressure and in a two-phase state, and the medium pressure is lower than a refrigerant pressure in a condenser and higher than a refrigerant pressure in an evaporator.

A valve apparatus includes a valve main body, a shaft body, a first valve element, and a second valve element. The valve main body has a first depressed portion and a second depressed portion in a circular shape, and a first port, a second port, and a third port each communicating with the first depressed portion, and a fourth port and a fifth port each communicating with the second depressed portion. The first port is allowed to selectively communicate with one of the second port and the third port by closure of one of the second port and the third port by the first valve element rotating about an axial direction. A flow amount of a fluid flowing between the fourth port and the fifth port is allowed to be variable by closure of the fourth port by the second valve element rotating about the axial direction.

An air conditioner 1 of the embodiment of the present invention, when all compressors 21a-21c have been stopping for a given time or more, starts an air conditioning operation without performing pressure equalizing control in switch units 6a-6d with starting the operation of the air conditioner 1. Also, when the stopping time of all compressors 21a-21c is less than the given time, the air conditioner 1 performs the pressure equalizing control by controlling switch units 6a-6d with starting the operation of the air conditioner 1. In this case, when the stopping time reaches the given time during execution of the pressure equalizing processing control, the pressure equalizing processing control being executed is stopped and the air conditioning operation is started.