An outdoor unit for a multi-type air conditioner includes a compressor, a four-way valve, an outdoor heat exchanger, an outdoor expansion valve, a liquid tank, an accumulator, a shutoff valve provided for the refrigerant pipe between a liquid refrigerant inlet/outlet port and the liquid tank in the outdoor unit, and a first bypass circuit provided in the refrigerant pipe for bypassing the shutoff valve through a capillary tube to connect a liquid refrigerant inlet/outlet port side to an upper side of the refrigerant pipe in a gravity direction. The outdoor unit further includes a second bypass circuit for connecting a bottom portion of the liquid tank to an inlet side of the accumulator via an electromagnetic valve.

In an air-conditioning apparatus, when a plurality of pumps are all operating and a heat exchange amount in use-side heat exchangers is equal to or lower than a lower limit of a thermal capacity that can be conveyed in a heat medium circuit B, before at least one of the plurality of pumps is stopped, a refrigerant flow path in the intermediate heat exchanger connected to the pump that is to be stopped is closed. Then, the at least one of the plurality of pumps is stopped, and the thermal capacity required in at least one of the use-side heat exchangers in the rest of the plurality of pumps is conveyed.

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.

In an air-conditioning system, an outdoor unit and an indoor unit communicate through a relay device, including a plurality of communication ports; a plurality of communication networks having logical connection relationships with the respective communication ports; and a plurality of nodes having logical connection relationships with the respective communication networks. The plurality of nodes are each associated with one of the outdoor unit and the indoor unit. Among the plurality of nodes, a certain node is set as a first node, and another certain node different from the first node is set as a second node. The relay device executes transfer processing of transferring a communication frame from the first node to the second node, and then if the relay device does not receive a reception acknowledgment signal from the second node, limits a number of re-transmission times when the relay device re-transfers the communication frame to the second node.

An air-conditioning apparatus includes a heat medium circuit in which a compressor, a flow switching unit, a flow regulating unit, a gas header, a heat source-side heat exchanger, a distributor, an expansion unit, and a use-side heat exchanger are connected by a pipe, and during a defrosting operation to defrost the heat source-side heat exchanger, heat medium circulates, in order, the compressor, the flow switching unit, the gas header, the heat source-side heat exchanger, the distributor, the expansion unit, and the use-side heat exchanger. The heat source-side heat exchanger includes a first heat exchange unit, and a second heat exchange unit provided lower than the first heat exchange unit. The flow regulating unit is configured to, during the defrosting operation, regulate a flow rate of heat medium flowing through the first heat exchange unit and a flow rate of heat medium flowing through the second heat exchange unit.

An air conditioner is provided that may include at least one compressor that compresses a refrigerant to a high pressure; a plurality of heat exchanger that condenses the refrigerant compressed in the at least one compressor; a plurality of outdoor valves, respectively, provided at an outlet side pipe of the plurality of heat exchangers; a gas liquid separator that separates the refrigerant into gas and liquid refrigerants and supplies the gas refrigerant to the at least one compressor; and one or more bypass devices connected to the outlet side pipe of one or more of the plurality of heat exchangers and an inlet side pipe of the gas liquid separator, the one or more bypass devices controlling a flow of the liquid refrigerant. During a cooling low load operation in which a portion of the plurality of heat exchangers is operating, a liquid refrigerant loaded into a heat exchanger of the plurality of heat exchangers, which is not operated, may flow through the one or more bypass device.

A heat pump hot-water supply apparatus controls a second expansion device during a heating operation so as to adjust the amount of refrigerant flowing through an injection pipe, and controls a third expansion device during a cooling operation so as to adjust the amount of refrigerant flowing through the injection pipe.

Task: To provide a high quality air conditioner with high efficiency and stability, preventing adverse effect of manufacturing variation on the refrigerant distribution.

Solution: The air conditioner having an expansion valve for decompressing a refrigerant, and a heat exchanger for heat exchange between the refrigerant and air. The air conditioner includes a first Linearly shaped piping that is connected to the expansion valve and vertically disposed, a branch pipe connected to the first piping for branching a refrigerant flow path into a plurality of sections, a plurality of second pipings connected to the branch pipe, and a plurality of distributors connected to the second piping for further branching the refrigerant flow path to the heat exchanger.

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.

A humidity regulating system comprises: a plurality of humidity adjusting devices to adsorb or vaporize the mist and water of the humidity adjusting rooms, a water regulating device to regulate the water supply to the humidity adjusting devices, a main controlling device to control the humidity regulating system, a communication connecting device to connect the plurality of humidity adjusting devices with the water regulating device and the main controlling device, and a remote controlling device which includes a remote controlling means to communicate with the main controlling device so as to regulate the plurality of humidity adjusting devices to adjust the humidity of the rooms.