"I bought this unit for a 12' by 22' room which is used as a lounge and office. It has a little higher cooling BTU than required for that size room, but it is the lowest cooling BTU in a unit (that fit the opening in the wall) that also functioned as a heater. I ordered the matching sleeve and that made installation fairly easy. The installation instructions assume you've done this kind of job before, but it wasn't too hard to figure it out. The unit incorporates some nice features such as auto fan and digital temperature setting. It does maintain the room temperature according to what you set. It's only downside is the air stream can only be directed in one direction, but in my size room it's not a big deal. Works really well as a heater. It is pure resistance heat, so it's not terribly efficient. But, again for the room size it's not a big money user. Did buy the aluminum exterior grill and it is much nicer that the kinda flimsy one supplied with the sleeve. Would buy again. [...]"