Mini-Split Ductless Air Conditioner

Ductless Splits have numerous residential and commercial applications. The most common residential applications are in multifamily housing or room additions.

 Commercial uses are also numerous. Some applications include elevator equipment rooms, computer rooms, telephone equipment rooms, schools, perimeter cooling for office buildings, additional cooling for restaurant kitchens, and cooling for small offices.

 These units combine the zoning flexibility of a conventional window unit (a single air conditioner installed through a wall or a window frame) with the whole house cooling potential of central systems.

 They have two main components:

  • Compressor bearing condensing unit
  • Air handling unit containing an evaporator and a fan. Some units operate as heat pumps and provide both summer cooling and winter heating.

 The term, “split system,” also describes the common central air conditioners and heat pumps. If you ask about ductless, air conditioners, make sure the dealer understands which system you are talking about. Another common term is “mini splits.”


The advantages over room and central air conditioners are:

  • Easy installation
  • Quiet operation
  • Versatility in zoning and design
  • No duct eliminating loss of cool air as it passes through the ductwork
  • Save energy, since only the rooms that are occupied need to be cooled
  • Independently controls each zone, operating costs are often lower than those of central systems that cool every room.
  • You can buy the system one zone at a time. A single outdoor unit controls from one to four zones, depending on the size of the unit.
  • Very high efficient units are available that use VRF, Variable refrigerant flow technology.
  • Typically, the Btu per hour rating (Btu/h) of these units ranges from 8,700 to 60,000
  • Air handlers can be suspended from a ceiling, mounted flush into a drop ceiling, or hung on a wall.


  • Units must be properly sized for the room to prevent short-cycling, which wastes energy and does not provide the desired temperature control
  • Some people may also not like the appearance of the exposed wall mounted air handling unit. While less obtrusive than a window unit, they seldom have the built-in look of a central system.
  • There must also be drainage for condensate outside the building. If the drainage is not well placed, the condensate can stain concrete or building materials. Condensate pumps can be required, something else to fail.


  • Cost is about $2,000 per ton (12,000 Btu/h) of cooling capacity.
  • VFR variable refrigerant flow units cost up to $6000 per ton