This 18,000 BTU Dual-Zone mini split ductless Air Conditioner with 22,000 BTU Heat Pump has three units: the compressor which sits outside of the home, and the 2 air handler which are mounted inside. A mini split air conditioner is very quiet and efficient, but it is more expensive than a window or portable air conditioner. Since they are ductless, the mini split AC/Heaters avoid the energy losses associated with the ductwork of central forced air systems.