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What is a Multi Split Air Conditioner

Multi split air conditioners work with multiple indoor and outdoor units for a building instead of with a single indoor unit and single outdoor unit as with traditional central air conditioning. These systems provide temperature control individualized to each zone, and zones can be as small as a single room depending on the setup. They are more energy efficient because zones that are not being used can be kept on minimal temperature settings rather than the system running full blast throughout the entire building.

Multi split air conditioners also hold several advantages over window units. Noise is significantly reduced because the loudest parts of its operation take place in the outdoor unit, which can be placed away from the building instead of in an open window. They are also more energy efficient, both because of their mechanical design and because they do not create insulation gaps because they do not need an open window. Further, they do not ruin the view and leave the windows to be opened on nice days.

How Do Ductless Split Systems Work?

Ductless systems combine one or more indoor units with a nearby outdoor unit. Rather than air being sent through the building via ducts, each indoor unit cools or heats air directly within the room or zone. The only connection needed to the outdoor compressor is a small hole in the wall for tubing that is just a few inches wide. There is a separate temperature control panel for each room or zone. With a ductless system, additional energy savings come from air not being lost to leaky ducts and energy not being spent to blast the air over long distances.

Multi Split Air Conditioner vs. Mini Split Air Conditioner

A mini split air conditioner is almost like a mini central air conditioner. It can cool or heat multiple rooms, but there is only one temperature control for the entire system. All indoor units connected within the mini split system turn on and off at the same time. Energy savings can still be achieved by designing some zones to cover rooms seeing more use or direct sunlight and putting rooms where less temperature control is desired into a separate zone.

A multi split system allows temperature control for the system to be divided into multiple zones. Each indoor unit has a direct connection to the outdoor unit and turns on and off based on its own temperature settings. When searching for a ductless split system, this feature is commonly referred to as "zone-control."

How to Install Multi Split Systems

Installation of a multi split ductless air conditioning system requires just a few simple steps:

  • Select a location for the indoor units. Models are available that hang on the walls and that sit along the floor next to the walls. The wall units are more efficient while the floor units are less obtrusive. The best location is along an exterior wall for ease of installation.
  • Select a location for the outdoor unit. The location needs to be on level ground, safe from flooding, and in close proximity to the desired location for each indoor unit.
  • Install the indoor units, either by hanging them on the wall or securing them to the floor. All materials are usually included and it is possible for one person to complete the job.
  • Install the outdoor unit. A concrete base is often used to ensure the unit stays level and stable and is protected from rain runoff. Be sure there is a path for water draining out of the air conditioner to flow away rather than pooling around the unit.
  • Drill the holes for the connecting tubing. This is why exterior walls are preferred; a direct connection with no need to snake the tubing through an interior wall makes for a simple installation. The units also lose efficiency with longer tubing.
  • Connect the tubing to the indoor and outdoor unit. Check for leaks before adding the refrigerant. Once everything is in place and working, seal any gaps between the tubing and the walls to ensure proper insulation.

How Much Do Multi Split Systems Cost?

The cost of a Mitsubishi Electric ductless air conditioner varies based on the power needed, the setup, and the features selected. A multi split system will run slightly higher than a mini split system. A single small room cooling only setup can start at around $1,500 dollars. Multiplying this by the total number of rooms can provide a rough guideline, but the number of variables makes accurate general estimates difficult. For a free estimate on a multi split system installation tailored to your specific needs, find a contractor near you at