In an air-conditioning system including a thermal storage heat exchanger, a refrigerant circuit is configured such that an indoor heat exchanger and a receiver communicate with the thermal storage heat exchanger when an operational mode of the refrigerant circuit is switched to a cooling operation in which the thermal storage heat exchanger serves as a radiator and the indoor heat exchanger serves as an evaporator.

An air conditioner including a distributor capable of adjusting the distribution of fluid flow to branched pipes is provided. The air conditioner includes a distributor configured to distribute a fluid flowing therethrough, and a heat exchanger including refrigerant pipes through which the fluid distributed by the distributor flows, the heat exchanger configured to heat exchange the fluid with air. The distributor includes an outer pipe having a cylindrical shape through which the fluid passes, and branched pipes. Each of the branched pipes includes one end connected to the outer pipe by being inserted into the outer pipe and includes a fluid passing part provided to allow the fluid to flow in or out. At least two branched pipes are configured such that at least one of an insertion length and a diameter of the fluid passing part inserted into the outer pipe are different from each other.

An air conditioner including a distributor capable of adjusting the distribution of fluid flow to branched pipes is provided. The air conditioner includes a distributor configured to distribute a fluid flowing therethrough, and a heat exchanger including refrigerant pipes through which the fluid distributed by the distributor flows, the heat exchanger configured to heat exchange the fluid with air. The distributor includes an outer pipe having a cylindrical shape through which the fluid passes, and branched pipes. Each of the branched pipes includes one end connected to the outer pipe by being inserted into the outer pipe and includes a fluid passing part provided to allow the fluid to flow in or out. At least two branched pipes are configured such that at least one of an insertion length and a diameter of the fluid passing part inserted into the outer pipe are different from each other.

A vertical fan unit includes a cabinet, a fan unit and a heating and cooling coil. A piping and valve assembly connects the heating and cooling coil to a four-pipe vertical riser. Shut-off ball valves are connected to respective hot and cold supply pipes of the vertical riser out of the path of air flowing through the heating and cooling coil. Hot and cold return valve assemblies include control ball valves connected to respective return pipes of the four pipe vertical riser and positioned adjacent the side wall out of the path of air flowing through the heating and cooling coil. A cable connects each temperature probe of the shut-off ball valves with respective BTU meters mounted at the control ball valves.

A vertical fan unit includes a cabinet, a fan unit and a heating and cooling coil. A piping and valve assembly connects the heating and cooling coil to a four-pipe vertical riser. Shut-off ball valves are connected to respective hot and cold supply pipes of the vertical riser out of the path of air flowing through the heating and cooling coil. Hot and cold return valve assemblies include control ball valves connected to respective return pipes of the four pipe vertical riser and positioned adjacent the side wall out of the path of air flowing through the heating and cooling coil. A cable connects each temperature probe of the shut-off ball valves with respective BTU meters mounted at the control ball valves.

A heat pump and a method for operating a heat pump are provided. The heat pump may include an outdoor unit including a compressor that compresses a refrigerant and an outdoor heat exchanger that exchanges heat between the refrigerant and outdoor air, a hybrid unit including at least one fluid-refrigerant heat exchanger that exchanges heat between the refrigerant supplied from the outdoor unit and a fluid, such as water, and at least one refrigerant control valve that controls an amount of refrigerant flowing through the at least one fluid-refrigerant heat exchanger, a plurality of indoor units each including an indoor heat exchanger that exchanges heat between the fluid supplied from the hybrid unit and indoor air, and a controller. The controller may calculate operation loads of the plurality of indoor units and control an opening degree of the at least one refrigerant control value based on the operation loads of the plurality of indoor units.

A heat pump and a method for operating a heat pump are provided. The heat pump may include an outdoor unit including a compressor that compresses a refrigerant and an outdoor heat exchanger that exchanges heat between the refrigerant and outdoor air, a hybrid unit including at least one fluid-refrigerant heat exchanger that exchanges heat between the refrigerant supplied from the outdoor unit and a fluid, such as water, and at least one refrigerant control valve that controls an amount of refrigerant flowing through the at least one fluid-refrigerant heat exchanger, a plurality of indoor units each including an indoor heat exchanger that exchanges heat between the fluid supplied from the hybrid unit and indoor air, and a controller. The controller may calculate operation loads of the plurality of indoor units and control an opening degree of the at least one refrigerant control value based on the operation loads of the plurality of indoor units.

A pipe joint structure includes: a union; a flare nut that includes a female thread formed at one of axially opposite ends of the flare nut, and a first annular surface formed at the other of the axially opposite ends of the flare nut; a cylindrical sleeve that houses the flare nut such that the flare nut can be rotate and moved forward and backward; a rotary ring that has a second annular surface located to face the first annular surface, and is attached to the sleeve such that the rotary ring can be rotated for the union; and a pressing member that presses the flare nut toward the rotary ring. At the second annular surface, a claw is formed in such a manner as to protrude towards the flare nut. The first annular surface includes an engagement surface that is formed in such a manner to face one side in a circumferential direction and a helically inclined surface that is adjacent to the engagement surface in the circumferential direction and formed helically in such a way as to incline and face the opposite side of the one side in the circumferential direction.

An air-conditioning apparatus includes a controller configured to operate in a heating normal operation mode and a heating-defrosting operation mode. In a case of switching from the heating normal operation mode to the heating-defrosting operation mode, the controller makes a selection from an initial control mode 1, in which control is performed such that an initial frequency of the compressor is set to a predetermined maximum frequency and an initial opening degree of the flow control device is set to an opening degree lower than a predetermined maximum opening degree, and an initial control mode 2, in which control is performed such that the initial opening degree of the flow control device is set to the predetermined maximum opening degree and the initial frequency of the compressor is set to a frequency lower than the predetermined maximum frequency, to execute the heating-defrosting operation mode.

An air-conditioning apparatus includes a controller configured to operate in a heating normal operation mode and a heating-defrosting operation mode. In a case of switching from the heating normal operation mode to the heating-defrosting operation mode, the controller makes a selection from an initial control mode 1, in which control is performed such that an initial frequency of the compressor is set to a predetermined maximum frequency and an initial opening degree of the flow control device is set to an opening degree lower than a predetermined maximum opening degree, and an initial control mode 2, in which control is performed such that the initial opening degree of the flow control device is set to the predetermined maximum opening degree and the initial frequency of the compressor is set to a frequency lower than the predetermined maximum frequency, to execute the heating-defrosting operation mode.