An air conditioning apparatus includes: an outdoor unit configured to circulated refrigerant; a first pipe and a second pipe that are connected to the outdoor unit; an indoor unit configured to circulate water; and a heat exchange device that connects the outdoor unit to the indoor unit. The heat exchange device includes a first heat exchanger and a second heat exchanger that are each configured to perform heat exchange between the refrigerant and the water, a plurality of connection pipes, a bypass pipe configured to guide the refrigerant passing through the first heat exchanger to the second heat exchanger, and a bypass valve installed at the bypass pipe.

An air conditioner and a fluid filling method for an air conditioner are provided. The method may include operating, by the air conditioner, in a fluid supply mode, to fill a group of pipes with a fluid, such as water, determining whether an amount of the fluid in the group of pipes is appropriate while continuously filling the group of pipes with the fluid, and outputting, by an output device, information indicating that filling of the fluid has been completed when it is determined that the amount of the fluid is appropriate. The fluid supply mode may include a first fluid supply mode in which fluid is supplied while the outdoor unit is stopped, and a second fluid supply mode in which the fluid is supplied while the outdoor unit is operated.

A hybrid multi-air conditioning system with no receiver is provided for optimal valve control. The hybrid multi-air conditioning system includes: a hot-water unit for exchanging heat between refrigerant and water; at least one indoor unit installed indoors and comprising an indoor heat exchanger and an indoor unit expansion valve; and an outdoor unit connected to the indoor unit and the hot-water unit via a refrigerant pipeline and comprising an outdoor heat exchanger, a compressor, and an outdoor unit expansion valve, wherein, when an abnormal refrigerant enters either the at least one indoor unit or the outdoor unit according to an operation mode, the abnormal refrigerant is shut off from the hot-water unit and the at least one indoor unit or the outdoor unit which operates as a condenser. Accordingly, the hybrid multi-air conditioning system improves heat exchange efficiency via direct heat transfer between refrigerant and water by having a coil wound on the water tank to transfer heat between refrigerant and water.

A present heating system or heating and cooling system does not include a tank for storing potable hot water in anticipation of a potable hot water demand. Although one or more temperature sensors may be used for providing feedback to heating of the contents of a tank water heater to achieve a setpoint temperature, the effect of stratification can cause layers of fluid having different temperatures in the tank water heater. Therefore, although portions of the contents of a water heater may be disposed at a setpoint temperature that is unfavorable for Legionella proliferation, there potentially exists other portions that may be disposed at temperatures suitable for Legionella proliferation, especially when the contents have been left unused for an extended period of time.

An air conditioning apparatus includes an outdoor device that is configured to circulate refrigerant and that includes a compressor and an outdoor heat exchanger, a plurality of indoor devices configured to circulate water, and a heat exchange device connecting the outdoor device with the indoor device. The heat exchange device includes a heat exchanger configured to exchange heat between the refrigerant and the water, and a switch device configured to control flow of refrigerant between the indoor devices and the heat exchanger.

An air conditioning apparatus is provided that may include an outdoor unit including a compressor and an outdoor heat exchanger and through which a refrigerant is circulated, an indoor unit through which a fluid, such as water is circulated, and at least one heat exchange device including a heat exchanger in which the refrigerant and the fluid are heat-exchanged with each other. The at least one heat exchange device may include a high-pressure guide tube that extends from a high-pressure gas tube of the outdoor unit so as to be connected to a first side of the heat exchanger, a low-pressure guide tube that extends from a low-pressure gas tube of the outdoor unit so as to be combined with the high-pressure guide tube, a liquid guide tube that extends from a liquid tube of the outdoor unit so as to be connected to a second side of the heat exchanger, and a solenoid valve installed in the high-pressure guide tube or the low-pressure guide tube to perform an opening and closing operation so as to allow the refrigerant to flow in a first direction. The high-pressure gas tube and the low-pressure gas tube may be connected to each other by a single gas tube, and when the indoor unit performs a cooling operation or a heating operation, flow of refrigerant in the first direction may be blocked in a state in which power is applied to the solenoid valve.

A plate heat exchanger includes a plurality of first heat transfer plates, a plurality of first inner fins, a plurality of second heat transfer plates, and a plurality of second inner fins. A space is formed between each of the plurality of first heat transfer plates and a corresponding one of the plurality of second heat transfer plates. The plate heat exchanger includes, in the space, a plurality of heat transfer components connecting each of the plurality of first heat transfer plates and a corresponding one of the plurality of second heat transfer plates, the plurality of heat transfer components being interspersed between each of the plurality of first heat transfer plates and a corresponding one of the plurality of second heat transfer plates. A recess-and-projection pitch section in each of the plurality of first inner fins includes first pitch sections and one or more of second pitch sections, a width of each of the second pitch sections being wider than a width of each of the first pitch sections. The plurality of heat transfer components are disposed in regions of the first pitch sections when the plurality of heat transfer components are projected in a direction in which the plurality of first heat transfer plates and the plurality of second heat transfer plates are stacked.

In a refrigeration cycle apparatus, each set of air heat exchangers among plural sets of air heat exchangers is one set of one or more of single heat exchangers, and the single heat exchangers each have an upper header pipe, a lower header pipe, a heat transfer tube, and a fin. During a cooling operation, a series refrigerant flow path is formed in which refrigerant flows in series through each set of the air heat exchangers; in the series refrigerant flow path, the refrigerant flows downward from above through the heat transfer tubes that all single heat exchangers have. During a heating operation, a parallel refrigerant flow path is formed in which the refrigerant flows in parallel through each set of the air heat exchangers; in the parallel refrigerant flow path, the refrigerant flows upward from below through the heat transfer tubes that all single heat exchangers have.

A temperature adjustment apparatus adjusts a temperature of a heating medium that exchanges heat with air in an indoor heat exchanger connected to a heat source apparatus. It includes a first and second pipes through which the heating medium flows, the second pipe being branched into a first and second branch pipes which are thereafter merged, a second heat exchanger in which heat is exchanged between the heating medium in the first branch pipe and the heating medium in the first pipe, and a flow rate regulator that changes a flow rate of the heating medium in the first branch pipe and a flow rate of the heating medium in the second branch pipe. The second pipe supplies the heating medium from the heat source apparatus to the indoor heat exchanger. The first pipe returns the heating medium from the indoor heat exchanger to the heat source apparatus.

When a state in which a driving voltage of a pump is set to an upper limit voltage and an opening degree of at least one of a plurality of flow rate control valves is set to a maximum opening degree continues for a first determination time period, an operation frequency of a compressor is raised at a first time so as to increase an amount of heat exchange by a second heat exchanger. When an operation stop request is input, or an indoor temperature reaches a set temperature, in at least one of a plurality of third heat exchangers after the first time, the operation frequency of the compressor is lowered or the driving voltage of the pump is lowered.