Ductless Mini Split Systems: The Ultimate Guide

uctless, mini split-system air-conditioners (mini-splits) offer numerous potential applications in residential, commercial, and institutional buildings. They are most commonly used in multifamily housing or as retrofit add-ons to homes with “non-ducted” heating systems, such as hydronic (hot water heat), radiant panels, and space heaters (wood, kerosene, propane). These systems are also an excellent choice for room additions and small apartments where extending or installing distribution ductwork for a central air-conditioner is not feasible.

How Ductless Mini Split Systems Work

How Ductless Mini Split Systems Work

Like central systems, mini-splits consist of two main components: an outdoor compressor/condenser and an indoor air-handling unit. These components are connected by a conduit that houses the power cable, refrigerant tubing, suction tubing, and a condensate drain.

Advantages of Ductless Mini Splits

Size and Flexibility

One of the main advantages of mini-splits is their small size and flexibility for zoning and cooling individual rooms. Many models can support up to four indoor air-handling units (for four zones or rooms) connected to one outdoor unit. This number depends on the cooling requirements of the building or each zone, which can be influenced by how well the building is insulated and air-sealed. Each zone has its own thermostat, allowing you to condition only occupied spaces, thereby saving energy and money.

Easier Installation

Ductless mini-split systems are often easier to install than other types of air conditioning systems. The connection between the outdoor and indoor units generally requires only a three-inch (~8 centimeters) hole through a wall for the conduit. Most manufacturers offer a variety of conduit lengths, enabling you to place the outdoor unit up to 50 feet (~15 meters) away from the indoor evaporator. This flexibility allows you to position the compressor in a more advantageous or inconspicuous location outside the building.

Energy Efficiency

Since mini-splits have no ducts, they avoid the energy losses associated with the ductwork of central forced-air systems. Duct losses can account for more than 30% of energy consumption for air conditioning, especially if the ducts are in an unconditioned space such as an attic.

Design Flexibility

Compared with other add-on systems, mini-splits offer more flexibility in interior design options. Indoor air handlers can be suspended from a ceiling, mounted flush into a drop ceiling, or hung on a wall. Floor-standing models are also available. Most indoor units have a profile of about seven inches (~18 centimeters) deep and usually come with sleek, high-tech-looking jackets. Many also offer remote controls for easy operation when the unit is positioned high on a wall or suspended from a ceiling.

Disadvantages of Ductless Mini Splits

Disadvantages of Ductless Mini Splits


The primary disadvantage of mini-splits is their cost. These systems typically range from $1,500 to $2,000 per ton (12,000 Btu per hour) of cooling capacity. This is about 30% more than central systems (excluding ductwork) and may cost twice as much as window units of similar capacity.

Installation Challenges

Correctly sizing each indoor unit and determining the best location for installation is crucial. Oversized or incorrectly located air-handlers can result in short-cycling, wasting energy and failing to provide proper temperature or humidity control. An oversized system is also more expensive to purchase and operate.

Aesthetic Considerations

While less obtrusive than a window room air conditioner, the indoor part of the mini-split system may not blend seamlessly with interior decor. Additionally, there must be a place to drain condensate water near the outdoor unit.

For more information, visit Cozy Heating And Cooling or call us at +1 202-681-9395. Our address is Woodbridge, VA. Check out our Energy Saver 101 infographic on home cooling to see how ductless mini-split air conditioners compare with other cooling systems.
call us at +1 202-681-9395
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