The BTU rating determines how powerful the air handler is. The higher the BTU, the bigger the room it can heat and cool.
Here are the recommended room sizes*:
- 9K BTU = Up to 375 Sq. ft room
- 12K BTU = Up to 500 Sq. ft room
- 18K BTU = Up to 750 Sq. ft room
- 24k BTU = Up to 1000 Sq. ft room
- 36k BTU = Up to 1500 Sq. ft room
*Ceiling height, insulation, and local climate may impact the coverage area. For example, an uninsulated room will require more power than a well insulated room.