Install air conditioner in horizontal sliding window

May 14, 2022 9:48 AM

I want to install a window air conditioner in a horizontal sliding window with a twist ...

Here is a photo with some drawing on it to show what I want:

I want to install the unit up high. Where the blue crosshatch is, I could cut a board (or possibly plexiglass) to size which would provide the support for the unit, though not balance.

Window opening is 20.5"

Is there a particular unit that would be best suited for this?
What can you suggest for the support structure?

posted by allelopath to Home & Garden (6 answers total)

What's the reason for wanting/needing to mount it up high? Doing that, rather than letting it rest on the sill (with a block of wood to make it level) makes if substantially more difficult to make it safe and secure. I absolutely wouldn't use a piece of plexiglas to support the weight (too much flex, and I doubt you'd be able to get any kind of strength rating for placing 70 pounds on the edge). The only way I would do this would be by building a frame out of 2 x 4s with two legs resting on the sill and two on the floor, and a platform on top for the AC unit to rest on. Then you could use plexiglas below to let light in.
posted by jonathanhughes at 10:13 AM on May 14, 2022 [6 favorites]

I have windows like this in my little mid-century house, and I installed a Frigidaire sliding-window air conditioner! I'm not sure the exact model exists anymore, but if you look up Frigidaire window-mounted slider/casement air conditioners, you'll find the right kind. This brand had the best option for my windows when I bought it a couple of years ago. I've had no problems with it and it has saved me while working from home during heat waves.

I'm with jonathanhughes that it'll be very difficult to ensure stability and safety if you try to put an air conditioner up high. When I installed mine, I had to attach a sturdy board to my siding to appropriately brace it because it was unevenly weighted and the outside part was much heavier. Also, this kind of air conditioner has a very short cord and stridently recommends against using an extension cord with it, which could be an issue if you raised it up. If you're trying to better cool the room by having the cooler air start up high, this isn't AS effective but you can angle the vents up?
posted by centrifugal at 11:36 AM on May 14, 2022 [1 favorite]

I have a Frigidaire FFRS0822S1, which is likely the same model centrifugal has. It's taller than it is wide, that is, like a typical air conditioner but turned on its side. Other manufacturers make similarly dimensioned ones (see under "Customers who viewed this item also viewed" at top of page from above link).

Yeah, I also think mounting it high is a bad idea. You really want the sill to take the weight of it. And given that this type of air conditioner is already taller than a normal one, you do have the vents already higher.
posted by ShooBoo at 11:56 AM on May 14, 2022 [3 favorites]

If the concern is that you don't want to block the bottom of the window (view, etc), you could get one of those U-shaped air conditioners that fits over the bottom sill and extends downwards.
posted by Nickel at 1:16 PM on May 14, 2022 [3 favorites]

As Nickel says, if the issue is keeping the view through the windows, Soleus sells "saddle" air conditioners which hang over the sill. Looking at the specs, the 6000 and 8000 BTU models are 18.7" wide, which should fit your window opening.
posted by ShooBoo at 2:27 PM on May 14, 2022 [2 favorites]

Do you have floor space near the window? If so, what about a portable air conditioner?
posted by eviemath at 7:09 AM on May 15, 2022