There are five types of compact air conditioner units: portable, window, through-the-wall, ductless mini-split and packaged terminal. Compact air conditioners are used to keep smaller spaces cool and to maximize energy-efficiency. Any of these five types could be used as a primary source of cooling or as a supplement to a central cooling system.
A portable air conditioner unit can be moved to different rooms as needed. It must be near a window for the exhaust setup. This style is best for cooling single rooms or small apartments, or for adding supplementary cooling in computer rooms.
A window air conditioner is installed inside of an open window. It can provide a primary source of air conditioning or can be used to supplement the air conditioning of up to two rooms.
Thru-the-wall air conditioners are like window units but they are installed in a wall with exterior access. They can cool up to two rooms and are sometimes more aesthetically pleasing than window units.
A ductless mini-split system is the quietest of the compact units. It can provide efficient cooling for up to four rooms. A ductless mini-split system is great for interior rooms that do not have windows or exterior walls. A packaged terminal unit is a commercial grade air conditioning system. It is a cooling and heating system that is installed in a wall. These types of units are best for the hospitality industry or for any space that needs both heating and cooling.