Advice on thru-wall AC units

July 4, 2007 7:31 PM

I am moving into an apartment with a pre-existing wall hole for a thru-wall AC. (It's a Fedders building -- but I don't need a Fedders unit, right?) Despite my best google search skills, I'm having trouble figuring out what exactly I need to make this work. Help!

The pre-existing opening (about 27 x 17 x 17, I think it's the "A" chassis size) is lined/fitted with a thin metal box. Is that the same thing as the "sleeve," or is it just the way the opening was finished off when the building was constructed? The units I am looking at (which are wall/window convertible ACs -- waaay cheaper than solely thru-wall, and also with the lower BTU that's all I need for my small room) are smaller than the opening. I know that if it's not a tight fit I could stop the gap with foam, but these are considerably smaller (28 x 12 x 12) -- can I put side extenders or something onto it? What about if the height? Is it a problem if the depth of the unit doesn't extend past the depth of the opening? Advice from anyone with wall unit experience would be appreciated!

posted by alleycat01 to home & garden (5 comments total)

I've only lived in one place like the one you describe, so take this with a grain of salt, but in my experience, as long as the AC is smaller than the metal box, you'll be fine. Most window AC's come with side extenders already, so all you'd have to do is secure those to the frame of the sleeve (or of the wall if it's flush), put some foam at the top, and you should be good to go.
posted by pdb at 8:23 PM on July 4, 2007

Thanks, pdb. So you think foam will work even if the difference btwn the opening and the unit heights is 5 inches? That seems like a lot to stop up.

(And btw, I meant I was looking at units that were 18 inches wide, not 28 which is obviously too large for the opening!)
posted by alleycat01 at 8:40 PM on July 4, 2007

I'd say you're fine - don't overthink it. As long as you can secure the unit in the opening to your satisfaction (i.e, it's not going to fall out and plummet to the ground below) you will be fine. Stuff whatever you have to in the spaces to fill them up. It may look like hell, but it will cool your apartment just as effectively as a purpose built "through-wall" unit.
posted by davey_darling at 8:48 PM on July 4, 2007

So you think foam will work even if the difference btwn the opening and the unit heights is 5 inches

Yeah - but an easier, albeit less aesthetically pleasing, solution is to stuff an old bath towel in the opening. As davey_darling says, though, as long as the unit doesn't pose any danger of falling out, everything else is secondary.
posted by pdb at 9:02 PM on July 4, 2007

The big constraint is going to be vents and intakes -- make sure your window unit only vents cold air on the front (not on the top, bottom or sides) and has its intakes only on the back (not on the top, bottom or side).
posted by MattD at 7:12 AM on July 5, 2007