An indoor unit includes a main unit including an air inlet through which air enters from a room and an air outlet through which air blows into the room, an electrical component box mounted on an outer surface of the main unit and accommodating an electrical device, a refrigerant pipe connection portion to which a refrigerant pipe through which refrigerant passes is connected, a drain pipe connection portion to which a drain pipe through which drain water discharged from the main unit passes is connected, and an installation bolt attachment bracket mounted on the outer surface of the main unit and fixing the main unit to an installation bolt suspended from above a ceiling. The indoor unit has the refrigerant pipe connection portion, the drain pipe connection portion, and the electrical component box on the same mounting surface.

A refrigeration system includes a supplemental heat exchanger operably disposed between a condenser and an evaporator. This supplemental heat exchanger is located in selective fluid communication with the air in the conditioned space, and can be toggled between an “invisible” mode in which the heat exchanger acts as a simple fluid conduit between the condenser and evaporator, and a “humidity reduction” mode in which the heat exchanger operates to transfer heat from hot refrigerant to the colder conditioned space. This addition of heat into the conditioned space decreases the relative humidity of the conditioned space and subcools the refrigerant leading to the expansion valve and evaporator. This subcooling of the liquid enables the evaporator to operate at a lower temperature which enhances the moisture removal from the air moving through the evaporator. The supplemental heat exchanger may be located in a physically elevated position relative to the remainder of the conditioned space to utilize stratification of hot air to create a default “invisible mode” without inducing airflow.

An indoor unit of an air conditioner includes a housing, a fan and a heat exchanger. The housing includes an upper base plate provided with an air inlet, a lower base plate detachably mounted to the upper base plate, and a front cover detachably mounted to the upper base plate; the fan is detachably mounted to the lower base plate; and the heat exchanger is detachably mounted to the upper base plate, in which the heat exchanger includes a supporting seat and a heat exchanger core body mounted to the supporting seat. The upper base plate is provided with a first positioning portion; the supporting seat is provided with a second positioning portion; and the first positioning portion cooperates with the second positioning portion to position the heat exchanger core body on the upper base plate.

A stub pipe housing and a method for installing a stub pipe housing in a heating, ventilation, and air conditioning (“HVAC”) system, the stub pipe housing comprising a first end for sealed contact with an external surface of a cabinet in the HVAC system and a non-permeable material extending to a second end for sealed contact with an external pipe. Sealed contact between the first end and the cabinet, sealed contact between the second end and the external surface, and the non-permeable material ensures any fluid escaping the connection between the stub pipe and the external pipe is directed to the cabinet. The stub pipe housing supports the connection using resilient material, rigid material with compliant seals or some combination. Fluids are directed to flow through the stub pipe opening in the cabinet or directed to flow through other openings.

A stub pipe housing and a method for installing a stub pipe housing in a heating, ventilation, and air conditioning (“HVAC”) system, the stub pipe housing comprising a first end for sealed contact with an external surface of a cabinet in the HVAC system and a non-permeable material extending to a second end for sealed contact with an external pipe. Sealed contact between the first end and the cabinet, sealed contact between the second end and the external surface, and the non-permeable material ensures any fluid escaping the connection between the stub pipe and the external pipe is directed to the cabinet. The stub pipe housing supports the connection using resilient material, rigid material with compliant seals or some combination. Fluids are directed to flow through the stub pipe opening in the cabinet or directed to flow through other openings.

An air conditioning system, including a compressor, two outdoor heat exchange units, a liquid pipe used for communicating with indoor units, a high-pressure gas tube and a low-pressure gas tube; the air conditioning system further includes a valve assembly. One outdoor heat exchange unit has a first state in which one end thereof communicates with the high-pressure gas tube and another end thereof communicates with the liquid pipe, and has a second state in which one end thereof communicates with the low-pressure gas tube and the other end thereof communicates with the liquid pipe. Further disclosed is a control method for the air conditioning system.

An air conditioning system, including a compressor, two outdoor heat exchange units, a liquid pipe used for communicating with indoor units, a high-pressure gas tube and a low-pressure gas tube; the air conditioning system further includes a valve assembly. One outdoor heat exchange unit has a first state in which one end thereof communicates with the high-pressure gas tube and another end thereof communicates with the liquid pipe, and has a second state in which one end thereof communicates with the low-pressure gas tube and the other end thereof communicates with the liquid pipe. Further disclosed is a control method for the air conditioning system.

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.

An air-conditioning apparatus includes an outdoor unit including an outdoor heat exchanger; an indoor unit including an indoor heat exchanger; and a relay unit provided between the outdoor unit and the indoor unit and including one or more first refrigerant supply pipes and one or more second refrigerant supply pipes that are connected to the indoor heat exchanger of the indoor unit. The one or more first refrigerant supply pipes and the one or more second refrigerant supply pipes protrude from the same side surface of the relay unit. The one or more first refrigerant supply pipes are each provided above an associated one of the one or more second refrigerant supply pipes. Part of the one or more first refrigerant supply pipes that protrudes from the side surface is longer than part of the one or more second refrigerant supply pipes that protrudes from the side surface.