Ductless mini-split systems are made up of an outdoor compressor and an indoor unit, which are connected by refrigerant and electrical lines. They are very quiet and are often used in retrofits.

The most common application for Ductless units are in multifamily housing or as retrofit add-ons to houses with "non-ducted" heating systems, such as hydronic (hot water heat), radiant panels, and space heaters (wood, kerosene, propane). They can also be a good choice for room additions and small apartments, where extending or installing distribution duct-work (for a central air-conditioner or heating systems) is not feasible. Applications in other types of buildings include: 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.

Mitsubishi "Mr Slim" Ductless System

Diagram of Ductless System

Life's Good LG – Duct-Free Air Conditioning Systems

Art Cool – Elegant, Efficient, Extraordinary Art Cool Duct-Free Mini-Split Air conditioning systems from LG maximize the efficiency and economics of duct-free technology. Now you can bring more attractive, cost effective solutions to your residence, providing single zone systems in both air conditioning and heat pump models.