Debating whether to install a honking-big window ac unit in a bedroom

July 27, 2022 10:17 AM

So I've got this 12,000 btu unit that's been sitting in my basement for well over a decade, thinking of hauling it upstairs and installing it in a small back bedroom. It's gonna be a pretty big project, involving a ladder, and probably quite a bit of aggravation, and I am a lazy, yet frugal, man.

Bought this bad boy July of 2001, and somehow, with the fervor of (relative) youth and the heat-induced madness of a Chicago summer, managed to haul it up to my 3rd floor walkup and install it. (Which is to say it's heavy & cumbersome.) It performed admirably for 8 years, cooling most of my 2 bedroom apartment, until I bought a house with central air. Perhaps foolishly, I took the unit with me, and it's been sitting in the basement lo these past 13 years.

Central a/c is great, but top floor of my little 2-story is always too warm in the summer. Finally bought a window unit for the bedroom, which I install/uninstall every season. I've got a back bedroom that could really use some a/c; why not the big guy?

I hauled it out of its corner, plugged it in & it seems to be working fine. Runs fan-only for awhile, then something clicks on and the cold air happens.

My concerns/questions are:

• It's old; like 21 years old. How long do these things last, anyway? (On the other hand, it's only been used for ~8 years...)

• Beyond running it for awhile, any other tests, things to look out for to indicate it's gonna fail 2 weeks after I put it in? Can they be repaired once installed?

• Cabinet will fit in the window, with 3/4" on either side...on the plus side, won't have to bother with those louver things; but it's gonna be a tight fit.

• There's bracket things for the cabinet, to help support it. I think they weren't needed at the apartment due to an exterior ledge. I've got the original installation guide; guess I'll figure it out? The house is old, 1912, seems to be a sturdy old gal, so I'm not that worried about weight...but should I be? The (newer) windows have some thin framing for the screen, I imagine that will be getting crushed...

• At the apartment, I ran it with a heavy-duty, a/c dedicated extension cord, and would be planning to do the same here, at least temporarily. It will never be run without me present. Safe enough?

• Obviously, it's way oversized for this application, but... so what?

• This will be a permanent installation (i.e., not taking it out in the winter). How bad could that be? Would it need to be covered up somehow come winter? (The window it will be in has a view of...nothing, really. Pretty ok giving that up. It will cut down any natural light, for sure)

Any knowledge you could lay on me would be very appreciated. Part of my hesitance is it took 3 tries to get the a/c working in my car, feeling a little gun shy re: air conditioning at the moment. I realize this is probably a FAFO situation, but as I said: lazy, lazy man. Thanks!

posted by Bron to Home & Garden (14 answers total)

Hermetic systems are way more reliable than shaft drive systems so the non use years shouldn't be a problem. Running these on an extension cord sized large enough is fine, the problem tends to come from the other damage an extension cord tends to be subjected to.
posted by Mitheral at 10:28 AM on July 27, 2022

Have you compared cost of running the AC you have with more modern options? The new inverter models are quiet and energy efficient enough that a new one might be worth it. Running an oversized AC can lead to issues with humidity if that's an issue where you live. It looks like you might be somewhere with a winter, which seems like it would be rough on your AC and you could wind up with leaks/drafts around where it's installed. There's enough small issues with this that I'd look for other solutions or just let that bedroom get hot.

If you decide to go for it anyhow, I split a furring strip I had around to keep from crushing my window frame ridges. They're like $2 for 8 feet, so you can have a few tries.
posted by momus_window at 10:50 AM on July 27, 2022

You might want to consider energy consumption / usage. Besides cost of electricity / environmental impact reasons you probably want to make sure the use of said machine isn't going to trip your circuit breaker/ fuse box. Also consider that "recommended" maintenance tends to assume that you will be bringing the unit inside at the end of the season.

Do you have some access to the unit from a nearby window? There exists the possibility that birds* will want to nest on top of your ac unit, and it might be helpful to have a sightline to the top of your window to observe this (and possibly take additional measures).

*with birds, comes bird poop
posted by oceano at 10:51 AM on July 27, 2022

Installing a 21 year old AC unit in a permanent installation seems short-sighted at best. Yeah, you’ll save money now - but what happens when it craps out in a few years and you have to replace it? Spend a little money on a new unit now and do it right the first time, so you won’t have to do it a second time.
posted by gnutron at 10:58 AM on July 27, 2022 [3 favorites]

This is a bad idea. Go to home depot and buy a 5000 BTU window AC for like $150. Or find one on Craigslist.

There's nothing wrong with reusing an old AC, although I'd be concerned about noise in a bedroom (newer window ACs are still no fun to sleep next to, buit are a little quieter)

Obviously, it's way oversized for this application, but... so what?

This is the real problem, and is why your plan is a bad idea. 12,000 BTU seems massively overspecced for any "small" room. That's not going to mean your room gets colder quicker. It's going to mean your room ends up humid and cold, among other problems.
posted by caek at 11:16 AM on July 27, 2022 [6 favorites]

Not only would a new unit last much longer, it would likely be much more energy efficient. And if you're in Chicago, you might want to consider a heat pump, which also provides heat and is much more environmentally beneficial. Window heat pumps are available, though that would require a bit of research to see if it would work for you.
posted by Mr.Know-it-some at 11:18 AM on July 27, 2022 [1 favorite]

Yeah no this seems like a sunk cost fallacy type situation -- sure you already own it, sure it still works, but it's definitely not what you want for this application. Sell it to someone who's still trying to cool an entire 2-bedroom apartment! It's been a sticky, hot summer here, I'm sure you'll have takers!
posted by We put our faith in Blast Hardcheese at 12:25 PM on July 27, 2022 [4 favorites]

I have a Chicago 1921 bungalow with central air and a second floor with tiny windows that doesn't get cool and -- just buy a Midea u-shaped window unit properly sized for the space. You will be so happy. I didn't take ours out this past winter although we bought covers for both the outside and inside halves of it... It was fine but got a bit drafty in the winter.
posted by misskaz at 12:26 PM on July 27, 2022

Obviously, it's way oversized for this application, but... so what?

So, there actually is a reason to care about this. Air conditioners that are too powerful for the space do a thing called "short cycling" where they work too quickly and then shut off, which means that they never get a chance to dehumidify. You end up with a room full of cold, clammy air.
posted by Ragged Richard at 12:28 PM on July 27, 2022 [2 favorites]

• It's old; like 21 years old. How long do these things last, anyway? (On the other hand, it's only been used for ~8 years...)

My parents have a big honkin' Friedrich window AC in their trailer house/near lake house that they got in 1982. They can last a long time, though the median age is probably not 40 years.
posted by The_Vegetables at 1:01 PM on July 27, 2022

I keep mentioning the Medea U air conditioners in every air conditioner question, but they really are a lot better, and so quiet, while also being more efficient that pretty much any other window unit. Literally off the charts on the yellow energy star sticker.

Also, oversized units cycle too quickly, which is hard on the unit but also doesn’t dehumidify the air properly.
posted by rockindata at 3:47 PM on July 27, 2022

Yeah, it would be worth it to get a new unit properly sized for the room and not such a beast to install. Give away the working old one to someone who needs it. It's hot out there!
posted by rikschell at 5:59 PM on July 27, 2022

$150 for a little one from Home Depot is a better way to go for sure. Apart from the energy and functional points others have raised, consider that “It’s so heavy it might crush the flimsy window framing” is a bad sentence when you’re talking about a huge metal box on the third floor.
posted by nouvelle-personne at 3:15 AM on July 28, 2022

Response by poster: Thanks for all the great advice here, everyone! The reality check I needed. And always good to be reminded of sunk cost fallacy, easily one of my top five fallacies.

The old guy is listed on Craigslist, and I'll be shopping for a new one.
posted by Bron at 7:20 AM on July 28, 2022 [2 favorites]