Some of the disadvantages involved with ductless air conditioners include a high initial cost and difficulty in servicing the devices. Difficulty determining the correct size ventless air conditioner for a room also creates issues for owners.
Ductless systems, particularly the mini-split variety, have a high initial cost. These units are small and portable, and multiple units may be needed to cool several rooms or the entire house. The initial cost can therefore be higher than installing a central system. They are, however, very energy efficient and help to save money on energy bills in the long term. They also offer more control when only certain parts of the home need to be cooled.
Qualified service and installation people can also be difficult to find for a ductless air conditioner. Most contractors invest heavily in training and tools for sheet metal duct systems and may be hesitant to recommend a ductless system. Portable units also require more maintenance and are not be able to run continuously for long periods of time like central cooling systems.
Ductless air conditioners are difficult to size and locate. Oversized units, for example, waste energy, have problems with short-cycling and do not effectively create a comfortable indoor temperature. Appliance buyers are advised to consult with a HVAC professional before buying a ductless air conditioner to ensure that the size matches their specific cooling needs.