Like central air conditioners, these units have a split design but without an elaborate system of ducts. The split system (also called a mini-splits, ductless split, or duct-free system) has at least one unit inside the home (this is the evaporator) and one outdoor unit (the condenser). Small tubes of refrigerant run from the outdoor unit to the indoor units – these are also known as line sets. Indoor units can be wall or ceiling mounted. Ductless splits can be used to cool one zone or multiple zones applying two to four indoor units to one condenser – the indoor units can all be used independently of each other.


A single zone ductless split system will have one evaporator, or air handler (indoor unit), and one condenser (outdoor unit). If you want to cool more than one area, a multiple zone split system applies two, three, or four (depending on the model) indoor units to one condenser. Normally its one unit per room – just make sure there is enough BTUs to cover the square footage in the room.

BTUs (British Thermal Units)

BTUs are units of power – the larger the area you need to cool, the more BTUs you need. To calculate the BTUs you need use our BTU calculator. This is very straight forward for a single zone split system. For multiple zone systems, both the outdoor units and the indoor units will have a set number of BTUs. One of the benefits of a ductless split system is that each indoor unit runs independently. Therefore, the total number of BTUs for the indoor units can exceed the outdoor unit’s BTU by up to 30%, but all the units cannot operate (on maximum) at once.

Installation Type

There are many different options of indoor units. One type of indoor unit is mounted on the wall. Select wall mounted units will come with customizable front panels that look like picture frames or pieces of art. Another type goes on the ceiling. Ceiling units can be suspended, recessed into the ceiling or concealed inside the ceiling. Ceiling units are for single zone applications only (multiple zone ceiling units are not available). Please keep in mind that ductless split systems have to be installed by a certified HVAC technician.

Ductless split air conditioners are a cost effective choice compared to central air conditioning. They are typically more expensive than wall or window air conditioners and you need an HVAC professional to install the unit. Since the compressor sits outside, ductless split air conditioners are very quiet and efficient. The indoor units do not need to vent through an exterior wall, so ductless splits are a good option to cool rooms with no windows and no exterior walls. A ductless split system also provides more temperature control because each indoor unit can be set independently from the other units.

Installing a ductless split air conditioner is more complicated that a window unit but far less complicated than installing central air. An HVAC professional will need to run lines for the coolant, electricity, and drainage. You will also need MMS to charge it with the right amount of coolants.

Request Service in Chicago and Northshore>>