An air conditioner capable of satisfactorily preventing noise from entering an indoor space includes: an indoor unit that is fixed to a wall surface of an indoor space and houses an indoor heat exchanger; and an outdoor unit that houses an outdoor heat exchanger connected to a refrigerant circuit that includes the indoor heat exchanger. The outdoor unit includes an outside casing that is fitted into an opening formed in a building wall partitioning an outdoor space and the indoor space from each other and defines an internal space that is open to the outdoor space and isolated from the indoor space by being surrounded by a sound insulation wall, and an inside casing that is disposed in the internal space and houses the outdoor heat exchanger.

Embodiments include overflow sensor assemblies for water heaters, HVAC systems, and other devices for which temperature control systems may be used. An example overflow sensor assembly for detecting fluid leaks at a device may include a sensor probe configured to be in electrical communication with a power supply, and a sensor mounting bracket that forms a ground, the sensor mounting bracket configured to attach to a mounting surface on the device and suspend the sensor probe in a condensate drain pan of the device. An overflow detection circuit can be activated when the sensor probe and the sensor mounting bracket come in contact with a condensate fluid.

An outdoor unit according to the present invention includes: a casing; and a heat exchanger accommodated in the casing. The casing includes a bottom panel on a bottom surface of the casing. The bottom panel includes: a first bottom plate portion formed below the heat exchanger; and a second bottom plate portion formed on the bottom panel at a portion other than the first bottom plate portion. A lower end of the heat exchanger is arranged at a position above any point on an upper surface of the first bottom plate portion and below any point on an upper surface of the second bottom plate portion.

A heat exchanger is provided and includes coils, a header disposed at an end of the coils to distribute fluid into the coils, an evaporator tube fluidly communicative with an end of the header and a tube sheet disposed against a side of one of the coils which is nearest to the end of the header to catch condensate dripping off the evaporator tube and to drain the condensate away from the coils.

An outdoor unit of an air-conditioning apparatus includes a housing, a heat exchanger, a bottom plate, a drainage structure, and a heating means. The housing has an opening through a side of the housing. The heat exchanger is disposed in an upper portion of the interior of the housing. The bottom plate is disposed at the bottom of the housing, and has a drainage hole through which to drain out drain water generated at the heat exchanger. The drainage structure is disposed below the heat exchanger and that guides the drain water to the bottom plate. The drainage structure includes a side panel that covers the opening of the housing, and a water guide plate disposed inside the housing and facing the side panel. The water guide plate and the side panel define a drainage path for draining the drain water between the water guide plate and the side panel.

An outdoor unit of an air-conditioning apparatus includes a housing, a heat exchanger, a bottom plate, a drainage structure, and a heating means. The housing has an opening through a side of the housing. The heat exchanger is disposed in an upper portion of the interior of the housing. The bottom plate is disposed at the bottom of the housing, and has a drainage hole through which to drain out drain water generated at the heat exchanger. The drainage structure is disposed below the heat exchanger and that guides the drain water to the bottom plate. The drainage structure includes a side panel that covers the opening of the housing, and a water guide plate disposed inside the housing and facing the side panel. The water guide plate and the side panel define a drainage path for draining the drain water between the water guide plate and the side panel.

An air conditioner includes: a first refrigerant tube that includes a first portion, and through which a liquid refrigerant flows; and a second refrigerant tube that includes a second portion that is disposed above the first portion and overlaps the first portion when viewed vertically, and through which a liquid refrigerant flows. The first portion is surrounded with a first heat insulating material.

An outdoor unit of an air-conditioning apparatus includes a housing, a heat exchanger provided in an upper part of an inside of the housing, and a control box disposed in the housing and configured to control the outdoor unit. The housing includes a base on which the control box is disposed and that is provided with a water drainage groove and a water drainage hole for draining defrost water generated on the heat exchanger to an outside, the base has three surfaces located at different heights that are, in order from top, a first surface, a second surface, and a third surface that is a bottom surface of the water drainage groove and is provided with the water drainage hole, and the control box is disposed on the first surface.

An external-air conditioning apparatus and a ventilation system are provided, the external-air conditioning apparatus includes a fin tube type heat exchanger and a housing that stores this heat exchanger. The housing includes a base body that serves as a back side of the apparatus body and a cover body that serves as a front side of the apparatus body, and the base body and the cover body are dividable and detachable in structure. The base body has a base portion, a partitioning portion, a connecting pipe portion, a heat-exchanger-holding structure portion, and a water receiving portion. The cover body is a structure in which a front wall portion and a three-side peripheral wall portion are formed integrally with each other, and a part in which the peripheral wall portion is not formed is an inlet for external air.

An external-air conditioning apparatus and a ventilation system are provided, the external-air conditioning apparatus includes a fin tube type heat exchanger and a housing that stores this heat exchanger. The housing includes a base body that serves as a back side of the apparatus body and a cover body that serves as a front side of the apparatus body, and the base body and the cover body are dividable and detachable in structure. The base body has a base portion, a partitioning portion, a connecting pipe portion, a heat-exchanger-holding structure portion, and a water receiving portion. The cover body is a structure in which a front wall portion and a three-side peripheral wall portion are formed integrally with each other, and a part in which the peripheral wall portion is not formed is an inlet for external air.