An air conditioner thru my wall?

May 19, 2009 10:45 AM

Thinking of putting our bedroom window air conditioner in the wall... bad idea?

Our bedroom gets quite warm on summer nights. We have a window air conditioner, which does the trick, but I hate blocking part of our one window, and it's across the room anyway so the cool air does not reach us well.

I'm considering putting it right thru the wall, closer to the bed. Cut an opening, frame it out, and put the a/c in. There's an electrical socket nearby. I figure we could cover it with a painting when not in use. In winter, I'd remove it, and put an insulated panel there.

All the same, a little voice in the back of my mind is saying... "maybe not a good idea self." I'm pretty handy, so the construction aspect is not a problem.

What do you think?

posted by ecorrocio to home & garden (23 comments total)

An old neighbor of mine did this and it looked ugly as hell. Seriously. Super, super trashy. Think about it.
posted by Optimus Chyme at 10:47 AM on May 19

Well, as long as you realize you are making an actual new window, and that comes complete with all your local building code guidelines and safety requirements... I don't see anything inherently wrong with that idea.

Closer to your bed will also mean louder, of course.
posted by rokusan at 10:48 AM on May 19

We had a similar situation in an upstairs room with a single window and got a Mitsubishi Mr. Slim ductless system. It requires one 3-inch hole in the wall. The inside unit is, if I remember correctly, about 14 inches tall. In our case we mounted it above the window.

It's super quiet, doesn't block the light, and is highly efficient. It's also not cheap, unfortunately.
posted by odinsdream at 10:51 AM on May 19

Instead of an "AC hole" why not just actually put a window in that spot?
posted by curlyelk at 10:56 AM on May 19

My parents did this with no problem. They put it sorta low in the wall so it wasn't too glaring. I think it looks better than being in the window! You can also properly fit the thing so you don't have gaps like most window units do.
posted by radioamy at 11:00 AM on May 19

My dad did this in our house. It worked fine, I guess, but we moved before the units had to be replaced so I don't know how much of an issue replacing them would have been.

Keep in mind this was on Long Island in the early 1970s when no one had central air (we had a oil burner and hot water heat) and insulation wasn't much of an issue (he just covered them in plastic for the winter months).

Central air, if you can afford it, is quieter, more efficient and doesn't adversely affect your outside walls.
posted by tommasz at 11:03 AM on May 19

The Mitsubishi Mr. Slim is one of a type of heat pump called a "ductless mini-split". While primarily an a/c unit they do apparently heat as well as are much more efficient/economical than electric baseboard or wall unit heat.

I'd be curious how "not cheap" they are as I'm considering something similar. On the bright side, they probably qualify for many of the energy efficiency tax credits out there now.
posted by msalt at 11:21 AM on May 19

The previous owners in our house did this. Infuriatingly, they did it directly below a window. It looked horribly trashy and the A/C unit itself probably dated back to the age of Cain, so our first order of business as new homeowners was to get that f-er out of there and reframe the subsequent hole and window above it into one big new window. The new window transformed our living room in terms of light and cross-breeze.

So while I'm obviously biased, I would implore you to not cut excess holes in your house unless you're making another window. Make it a nice tall one and you can put an A/C unit in the window and still have tons of light coming in above it.
posted by anderjen at 11:37 AM on May 19

I've been thinking of doing the same thing. There are air conditioners made for this.

And instructions.
posted by coolguymichael at 11:40 AM on May 19

I've done this with a Sears "window" unit with no problem. You get a tighter, more efficient fit than in a window, and probably quieter running as well (no vibrating window; a wall is a better sound insulator than glass). I caulked the bejeebies out of it and it's on a second-story wall, so there's no way I'd take it out each winter. You might consider just putting an insulating cover on the outside in winter.

An air conditioner in the wall doesn't have to look trashy. It's easier to make the unit hang at the proper angle, it fits snug in the wall instead of needing those cheapo accordion things, and it frees up the window to be a window.
posted by PatoPata at 11:40 AM on May 19

For the amount of money you would spend to prep the hole, insulation, you would probably be better off getting a portable air conditioner. Come winter, you just roll it away.
posted by zerokey at 11:44 AM on May 19

I'd say it depends on where you live. If you live in a place where the winters are milder than the summers then go for it if it floats your boat. If you live in a place with bitterly cold winters then you'd want to consider the loss of heating efficiency.

I know that in New England, where I live, you'd end up with a chilly, drafty, expensive to heat home come December. There are air conditioner covers that are supposed to prevent the drafts, but, in my experience, they aren't that helpful.

I also know that in Mississippi, where I used to live, you'd be just fine.
posted by Quizicalcoatl at 11:48 AM on May 19

We have this setup in our rental apartment. It works fine, and I don't think it looks particularly trashy--certainly no trashier than having it hang out a window. If anything, I would say it looks a little neater because it can be set in there really tight without that wobbly look that window units sometimes have. You can also position it lower than a window would normally be--ours is only a couple of feet off the ground (from the inside), making it somewhat less obvious from the street.

I'm on Long Island and as tommasz says, it's not an uncommon site here (even 30 years later, apparently!). In the winter the apartment manager puts metal covers on the outside of the units, but I will admit that this does not do much to insulate them.
posted by Jemstar at 11:53 AM on May 19

Re the cost: I cut a hole in the wall, used less than one 8' two-by-four to frame it and make a header, and squirted less than one tube of caulk. That would be a total price of about $12. The trickiest part was cutting the masonry siding. If you want to install molding around the unit, add another bit for that.

A window that is properly closed is more efficient than one that is held open by an air conditioner and thin expander panels. It also seems to me that you'd be more likely to get a leak-free A/C installation in a wall than in a window.
posted by PatoPata at 12:01 PM on May 19

I agree with odinsdream - a ductless a/c is the way to go. The condenser unit sits outside and through small piping the coolant is brought inside to the evaporator.

Upside: Easier wall install, doesn't take up a window, much smaller hole reduces thermal bridging, more freedom in placement, and more efficient.

Downside: Cost. These cost more then your typical window unit you pick up at Sears or (gasp!) the grocery store.
posted by spoons at 12:17 PM on May 19

tommasz writes "Central air, if you can afford it, is quieter, more efficient and doesn't adversely affect your outside walls."

Cooling an entire house is overkill if you just need to cool the bedroom.

There are air conditioners specifically made for this. Thru the wall units (similiar to the combination heat/cool units common in motels) have two design features that make them superior to adapted window units. 1) the business part of the unit mounts in a sleeve that is mounted in the wall. This allows easy servicing by sliding the unit out of the sleeve and into the room. Once the sleeve is installed it's as permanent as any other exterior fixture. 2) all the condenser venting (the part that gets hot) is straight out the back rather than at the sides. It's key to not block any vents on the case of the AC.

Installing a sleeve is fairly simple. Most thru the wall units are less than 32" wide so require only a light weight header for the single stud that needs to be cut.
posted by Mitheral at 12:49 PM on May 19

This is how all the AC units in my apartment are installed. Aside from any aesthetic considerations, which I can't comment on (it was how the place looked when we moved in, and I don't think it looks too bad, but then again I don't care), it seems to be a great solution.

It works well, the seal is better than the seal on a typical window unit (which I believe the units themselves otherwise are), and it's great to be able to put plants in our windowsill instead of a large machine.

I don't know about your situation, but this works for me.
posted by Ignatius J. Reilly at 1:04 PM on May 19

And I should add that during our nasty Chicago winters we don't notice any sort of draft or insulation problem either from the unit or from the area around it. Perhaps it's a particularly good install?
posted by Ignatius J. Reilly at 1:06 PM on May 19

Be very carefull, when you frame and finish this hole in the wall, to keep rain water out of the house. If the job is done poorly the water will come in at the top of the window frame, or will flow over the AC unit, and exit into the wall under the unit. Then it will soak your insulation and rot your frame. There is the issue of mold, as well. Have the unit slope slightly away from the exterior wall.
posted by Midnight Skulker at 1:08 PM on May 19

Our last apartment had two wall units. One caution if you go that route: our landlord got a unit that was too powerful for the bedroom because it was on sale. We only used it when we absolutely had to because it was so loud.
posted by betsybetsy at 1:12 PM on May 19

The previous owner of my house did this and I HATE it. Cold air leaks in during the winter, and in the summer, it's not powerful enough to cool the living room and the kitchen it opens into, so I end up having to put window units in anyway. As soon as I get central air, I'm tearing it out and patching the wall. It would've been much easier had she just put it in the window like everybody else.
posted by TrialByMedia at 2:23 PM on May 19

I'd be curious how "not cheap" they are as I'm considering something similar. On the bright side, they probably qualify for many of the energy efficiency tax credits out there now.

I only meant they aren't cheap if you're comparing them to a window unit. Though it's really not a fair comparison. I would definitely get the Mr. Slim again and would highly recommend it. It's very quiet. I mean, really...really quiet. Especially the outside portion. I literally cannot hear it from a foot away. The installation only took a few hours and the outdoor unit is capable of running more than one internal unit. This is great in our case since we're planning an expansion next to the existing room. When we finish that we'll just get another internal unit and hook it up to the same outside compressor.

Mine is a heat-pump model, not just AC, though that was a mistake on the installer's part. If you have any questions just send me a mefi-mail.
posted by odinsdream at 3:31 PM on May 19

the Mr. Slim and equivalents (there are tons) are very very common in the rest of the world. They are more expensive, but they come with remotes, are programmable for on/off times etc, and are generally much nicer looking than window a/c units. I'm not sure why they are not common in North America.
LG Room A/C
Fujitsu Room A/C
posted by defcom1 at 8:32 PM on May 19 [1 favorite has favorites]