The second name of ductless air conditioners is “mini-split” systems because they are the same as a regular ducted split central air conditioner, but first units are on a smaller scale. A split system means that the compressor/condenser device, which is placed outside the house and “split” from the indoor cooling coils/blower. Just a small three-inch diameter hole is cut in the wall to run the tiny refrigerant lines and electric wires to the indoor cooling devices.
The compressor outdoors and an indoor cooling unit mounted high on a wall or ceiling are very quiet. You can hear the only sound from them – something like “whoosh”. Many ducted central air conditioners are louder than these devices. In a central unit, huge amounts of air must be pushed through complex ducts with many bends and shape changes. So all these activities create a noise.
Mini-split air-conditioners are a recommended option to use several room air conditioners to cool an entire home. Window may be blocked by window air conditioner devices.
In our days rates of the efficiency of ductless units (SEER: 10-19) are as high or higher as the top-of-the-line central air conditioner (SEER up to 16), and they can still have higher efficiency than wall, window and even central devices. Mini splits do not have ducts, that is why they do not have airlosses. Duct losses can account for more than 30 percents of consumption of energy for space conditioning, especially if the ducts are in a unconditioned space, for example, attic.
Heat pump units also have an ability to keep warm. If you hate that first shot of chilly air in the winter each time the furnace or heat pump blower starts its operating processes, you should choose a model, which has no ducts, with a soft, slow start and a pre-heater for the air. For colder climates, some of the heat pump units also have backup electric resistance heat.
Mini split-system air-conditioners, which have no ducts and heat pumps (mini splits) have many available applications in residential, commercial, and institutional buildings. The most common units are in multifamily housing or as retrofit add-ons to homes, which have “non-ducted” heating systems, such as hydronic (hot water heat), radiantpanels, and space heaters such as convectors.
They can also be a nice option for room additions and small apartments, where extending or installing distribution ductwork (for a central air-conditioner or heating systems) is not available. Units in other types of buildings are the following: recording studios, school classrooms; perimeter cooling for office buildings; additional cooling for restaurant kitchens; and cooling for small offices within larger spaces, such as arenas, warehouses, and auditoriums.
The main drawback of mini splits is their price. Although, costs have decreased dramatically during the past few years, such systems can cost about $600-$2,000 per ton (12,000 Btu in one hour) of cooling capacity. This is about 10 percents more than central systems (it is not about the ductwork) and may cost twice as much as window devices of the same capacity.
The installer must also properly size each indoor device and judge the best place for its installation. If your air-handlers are sized and located incorrectly, you will get the result in short-cycling, which wastes energy and does not provide needed temperature or humidity control. You should remember that system of bigger size has higher price of purchase and operation.