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Types of Home Air Conditioning Systems and How They Work


ductless air conditioner

Some ductless air conditioners come with remote controls since they are mounted high on a wall, such as this Sanyo unit, model KS1872.

© Sanyo 2011
The terms used to describe types of air conditioners and how they work can be confusing. There are unitary, PTAC, window, portable, central, split, ductless systems and so on. In this tutorial we will review the most commonly used air conditioning and cooling systems in the home and their terminology.

Types of Cooling Systems
There are several types of cooling systems you may have in your home. They range from units installed in a window, to units rolling around on the floor, to units mounted on a wall, to central air conditioning. All the systems use the same five elements of an air conditioning system consisting of refrigerant, compressor, condenser, expansion valve, evaporator coil as described in How Air Conditioning Works. Let’s review the most common types of air conditioning systems in the home.

  • Window Air Conditioner This system is technically called a "unitary" air conditioning system and consists of a self contained air conditioning unit that is placed in a window or through a hole in an exterior wall. Since adding holes in your home’s outside walls are not a really good idea, these units are almost always placed in a window. The unitary system has all the refrigeration components on one compact box. It ejects heat out one end and blows cooled air out the other end.
    Compare Prices Window Air Conditioner Options

  • Portable Air Conditioner This system is another flavor of the unitary air conditioning system. The portable air conditioner consists of a mobile self contained air conditioning unit that is placed on the floor inside a room and discharges exhaust heat using a hose vent through an exterior wall. Portable air conditioning units are a bit noisier than other types of units and can typically cool rooms under 500 SF. These units are a solution to those stubborn hot rooms that may exist even with central air conditioning. Like the window air conditioner, the portable unitary system has all the refrigeration components on one compact box. It also ejects heat out one end and blow cooled air out the other end.
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  • Split or Ductless Air Conditioner The split system or ductless system is technically called a "packaged terminal air conditioner" or PTAC. You see these occasionally in home applications but more commonly in hotels, motels and apartments. The split system breaks the air conditioning system into two packages or terminal units and refrigerant tubing passes through the wall connecting both package units.

    One terminal package is the condensing unit located on the exterior and includes the compressor, condenser and condenser fan. The other terminal package is the evaporative unit located on the interior and handles air cooling and distribution. The internal evaporative unit includes the fan, expansion valve and evaporator coil.
    Compare Prices Split / Ductless Air Conditioner Options

  • Central Air Conditioning The central air conditioning system is the premium cooling solution for your home. It is the quietest, best performing and most comfortable. The only real risk is that the system be sized appropriately for your home. If it is sized too large it will not perform well and will not adequately dehumidify and may also short cycle.

    The central air conditioning system is made up of two packaged units, the condensing unit and the evaporative unit. Both are connected by refrigerant tubing. The condensing unit is the large boxy unit that sits outside and consists of the compressor, condensing coils and condensing fan. The evaporative unit typically sits in the plenum of your furnace so the air conditioning can use the same ductwork as your heating system. In the plenum, the evaporative unit consists of the evaporator coil and expansion valve.
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