AC Types 3D

Split AC systems and heat pumps generally consist of two main parts: an indoor unit (with an evaporator and metering device) and an outdoor unit (compressor and condenser) connected by linesets (the suction or vapor line and the liquid line). Heat pumps also have a reversing valve that can reverse the flow direction. These systems may be paired with a furnace (if a heat pump is paired with a furnace, it will be called a “dual-fuel” system).

Package systems combine the evaporator, compressor, and condenser into a single outdoor unit. These units may either be on the ground or on rooftops and rely on ductwork to move air into the unit from the structure and out of the unit back to the structure.

Packaged terminal air conditioners (PTACs) and vertical terminal air conditioners (VTACs) are self-contained units common in hotels and apartments, though with reduced efficiency. They require an outdoor penetration for heat exchange. Window units are also self-contained and can exchange heat between the indoors and outdoors. Ductless or mini-split units and variable refrigerant flow (VRF)/variable refrigerant volume (VRV) systems are usually split systems that move BTUs efficiently in concentrated spaces (such as individual rooms).

Ductless mini-splits often have one head, and VRF/VRV systems often have multiple heads that can serve multiple rooms. They are best in applications where duct installation is impractical, high efficiency is desired, or precise temperature control is needed. In many mini-splits, the metering device is outdoors, so there are two cold lines that require insulation, not just one.

Water-source or geothermal heat pumps use the stable temperatures of water or the ground, not air, to exchange heat. All components are indoors, including the compressor. While highly efficient, they need a lot of space so that we can create the well or ground loop needed for heat exchange to occur.

Swamp coolers (evaporative coolers) rely on adiabatic cooling to reduce the temperature of incoming air. As air moves over the wet cooling pad, some of the water absorbs heat from the air, leaving the air cooler as it leaves. These are common in hot, dry climates, and microbial growth is a concern that we must consider.

Monoblock heat recovery chillers contain all components in a single unit, utilize secondary fluids, and produce heated and cooled fluid simultaneously. These units may be used for heating, cooling, dehumidification, and domestic hot water. Their designs are a bit more complicated, and they require you to consider the placement of buffer tanks where the heated and cooled fluids are stored.

Each AC system type has its own advantages, applications, and ideal installation conditions.

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