The ASHRAE btu’s rating (6000 btu’s) is subtracted from the total btu’s rating (10,000 btu’s). This true rating is the best as to change the hot gas freon to liquid a portion (40% or 125 cfm or 4k btu’s) of the interior air is used to cool the condenser. The compressor and condenser are mounted in the portable cabinet. A split system (standard in most homes) has the compressor and condenser outside with evaporate and blower are mounted inside.