Abstract: When using at least one of heat exchangers related to heat medium that exchange heat between a heat source side refrigerant and a heat medium as an evaporator, in a case where an air-conditioning apparatus has detected, in the heat exchanger related to heat medium that functions as the evaporator, an evaporating temperature of the heat source side refrigerant which causes the temperature of the heat medium passing through this heat exchanger related to heat medium to become equal to or lower than a freezing temperature, the air-conditioning apparatus performs a heat medium anti-freezing operation by blocking entry of the heat source side refrigerant into the heat exchanger related to heat medium that functions as the evaporator, and causing the heat source side refrigerant to flow to a bypass pipe.

Abstract: Obtained is a heat medium relay unit capable of having improved serviceability and an air-conditioning apparatus equipped with the heat medium relay unit. Heat medium flow control devices are each disposed below a corresponding one of the first heat medium flow switching devices. The heat medium flow control devices are similarly disposed in a zigzag manner along with the zigzag arrangement of the first heat medium flow switching devices.

Abstract: In an air-conditioning apparatus, an expansion device, a second refrigerant flow switching device, and heat exchangers related to heat medium, connected between the expansion device and the second refrigerant flow switching device such that a heat source side refrigerant flows in parallel, are connected in a part of refrigerant passages, and an expansion device, a second refrigerant flow switching device, and heat exchangers related to heat medium, connected between the expansion device and the second refrigerant flow switching device such that the heat source side refrigerant flows in series, are connected in the rest of the refrigerant passages.

Abstract: A refrigeration cycle that is formed by connecting a compressor, a condenser, expansion means, and an evaporator and that performs cooling operation; an evaporator heating device that heats the evaporator; a drain pan that receives drain-water from the evaporator and drains the drain-water; a drain-pan heating device that heats the drain pan; frost detecting means including a light-emitting element that emits light to the evaporator and a light-receiving element that receives reflected light from the evaporator and outputs a voltage according to the reflected light; and a control device that controls on-off operation of the evaporator heating device and the drain-pan heating device. The control device determines a frosting condition on the evaporator from an output of the frost detecting means and individually controls the evaporator heating device and the drain-pan heating device in accordance with the determination result.

Abstract: To provide an air-conditioning apparatus that reduces large refrigerant noise generated when changing an operation mode. In an air-conditioning apparatus, when switching to a second operation mode from a first operation mode, switching to the second operation mode is performed after a predetermined time has elapsed after controlling either or all of expansion devices, controlling either or all of second flow switching devices, and controlling either or all of a first on-off device and a second on-off device such that a pressure difference of a heat source side refrigerant before and after each of the expansion devices is smaller compared to that in an operation state of the first operation mode.

Abstract: To obtain an air-conditioning apparatus that is capable of performing an effective defrosting operation, as well as saving energy, the air-conditioning apparatus has a heating operation mode that heats a heat medium in at least one of the heat exchangers related to heat medium, a heat recovery defrosting operation mode that melts frost attached to a heat source side heat exchanger—during the heating operation mode by operating at least one of the pumps and by making a heat source side refrigerant receive heat from the heat medium that is flowing in the at least one of the heat exchangers related to heat medium, and a bypass defrosting operation mode that melts frost attached to the heat source side heat exchanger during the heating operation mode by passing a portion or all of the heat source side refrigerant through a bypass piping.

Abstract: An air-conditioning apparatus includes a heat medium circuit that circulates a heat medium different to the refrigerant on a heat source side. The heat medium circuit includes, for example, heat exchangers related to heat medium, use side heat exchangers, first heat medium flow switching devices and second heat medium flow switching devices that change passages of the use side heat exchangers, heat medium flow control devices that controls a heat medium amount in the corresponding use side heat exchangers. An on-off device is each provided on the upstream side of the heat medium flow control device and on the downstream side of the second heat medium flow switching device and a first backflow prevention device is each provided on the downstream side of the heat medium flow control device and on the upstream side of the first heat medium flow switching device.

Abstract: To provide an air-conditioning apparatus capable of achieving energy saving. In an air-conditioning apparatus, a first housing (an outdoor unit) that accommodates a compressor and a heat source side heat exchanger; a second housing (a heat medium relay unit) that accommodates a heat exchanger related to heat medium, an expansion device, and a pump; a third housing (a heat medium regulating unit) that accommodates a first heat medium flow switching device, a second heat medium flow switching device, and a heat medium flow control device; and a fourth housing (indoor unit) that accommodates a use side heat exchanger have separately different casings.

Abstract: An air-conditioning apparatus that that is capable of saving energy is provided. An air-conditioning apparatus includes a refrigerant indoor unit that air-conditions a conditioned space by using a heat source side refrigerant supplied from an outdoor unit, and a heat medium indoor unit that air-conditions a conditioned space by using a heat medium different from the heat source side refrigerant. The air-conditioning apparatus includes a first heat medium relay unit that is supplied with the heat source side refrigerant from the outdoor unit, a third heat medium relay unit interposed between the first heat medium relay unit and the refrigerant indoor unit, and a third heat medium relay unit interposed between the first heat medium relay unit and the heat medium indoor unit.

Abstract: An air-conditioning apparatus includes a refrigerant circuit having a plurality of expansion devices that controls a flow rate of the refrigerant flowing in each of a plurality of heat exchangers related to heat medium; a heat medium circuit having the heat exchangers related to heat medium and a use side heat exchanger that exchanges heat between the heat medium and air; heat medium flow switching devices disposed on an inflow side and an outflow side of the use side heat exchanger to mix or diverge the heat medium pertaining to the heat exchangers related to heat medium; and a controller that controls at least the heat medium flow switching device on the inflow side or the outflow side that controls the amount of heat exchange in each of the heat exchangers related to heat medium during cooling only operation mode or heating only operation mode.

Abstract: A refrigeration cycle apparatus including a heat source side heat exchanger including a first heat exchanger and a second heat exchanger connected in parallel; an air-sending device that supplies air, which is an object to be heat exchanged in the first heat exchanger and the second heat exchanger, in a variable manner; solenoid valves that each opens and closes a refrigerant passage of the first heat exchanger and the second heat exchanger; a third refrigerant circuit that is parallelly connected to the first heat exchanger and the second heat exchanger; and a flow control valve that controls the flow rate of the refrigerant flowing in the third refrigerant circuit. The refrigeration cycle apparatus can improve continuity of control of a heat exchange capacity of a heat source side heat exchanger.

Abstract: An air-conditioning apparatus including an outdoor unit having a compressor compressing a refrigerant and a heat source side heat exchanger exchanging heat between the refrigerant and air; a plurality of indoor units having use side heat exchangers exchanging heat between a heat medium that flows therein and air; and a relay unit disposed between the outdoor unit and the indoor units, the relay unit exchanging heat between the refrigerant conveyed from the outdoor unit and the heat medium flowing in the indoor units, in which the relay unit includes a main relay unit that is connected to the outdoor unit with two pipings and a sub relay unit that is connected to the main relay unit with three pipings.

Abstract: To provide an air-conditioning apparatus capable of achieving energy saving. An air-conditioning apparatus includes at least a use side heat medium flow control device and a first heat medium flow switching device disposed in an outlet side of the heat medium passage of a use side heat exchanger, and a heat medium backflow prevention device disposed in an inlet side of the heat medium passage of a use side heat exchanger.

Abstract: An air-conditioning apparatus includes indoor units including a plurality of use side heat exchangers that exchange heat between air and a heat medium, and a heat medium relay unit having a plurality of heat exchangers related to heat medium. A plurality of pumps deliver the heat medium involved in heating or cooling performed by the plurality of heat exchangers related to heat medium to each passage and circulate the heat medium. A plurality of heat medium flow switching devices perform switching so that the heat medium from a selected passage flows into and flows out of each use side heat exchanger. An expansion tank is connected to a passage alleviates a pressure change caused by a volumetric change of the heat medium, and a pressure equalizing pipe connects each inlet passage or each outlet passage of the heat medium sending devices.

Abstract: Obtained is an air-conditioning apparatus that is capable of saving energy. A pressure in a passage of the second refrigerant flow switching device in which a refrigerant from an outdoor unit flows into is higher than a pressure in a passage of the second refrigerant flow switching device in which the refrigerant flows out to the outdoor unit regardless of switching states of a first refrigerant flow switching device, the second refrigerant flow switching devices, and a third refrigerant flow switching device.

Abstract: A heat medium relay unit and an air-conditioning apparatus or the like are provided that are compact and have improved serviceability while achieving energy saving. A heat medium relay unit according to the invention includes heat medium delivering devices and heat medium flow switching devices (first heat medium flow switching devices and second heat medium flow switching devices) that are provided so as to be detachable from a predetermined side.

Abstract: To provide an air-conditioning apparatus capable of achieving energy saving. The air-conditioning apparatus capable of executing an oil collection mode that collects a refrigerating machine oil stagnating in heat exchangers related to heat medium into a compressor by changing a flow velocity or a flow direction of the refrigerant flowing in the heat exchangers related to heat medium depending on each operation mode.

Abstract: To provide an air-conditioning apparatus capable of achieving energy saving, a pump control of controlling the operating capacity of a pump is performed such that an opening degree of a heat medium flow control device, controlled by a heat-medium-flow-control-device control, approaches a target opening degree, and a refrigeration cycle of a refrigerant circuit is controlled such that the temperature of a heat medium, whose flow rate is controlled by the heat-medium-flow-control-device control and the pump control, approaches a target temperature.

Abstract: To provide an air-conditioning apparatus capable of achieving energy saving. An air-conditioning apparatus controls first heat medium flow switching devices and second heat medium flow switching devices in a heating only operation mode and a cooling only operation mode such that a flow rate through which a heat medium circulates is formed between all of the heat exchangers related to heat medium and at least one of use side heat exchangers.