I have a window well in a basement where I'd like to setup a portable AC unit (~10000 BTUs). There is a cover that I need to keep in place to avoid water collecting in the window well, but I could possibly keep this open a bit. How do I calculate the threshold for the exhaust of this hot air?

  • Besides exhausting the hot air, you'd also have to assure a supply of cool air. Cracking the cover won't cut it. You'd have to either install some forced air handling, or get a hose type a/c and install its hoses through the cover, taking care to protect them from inclement weather.
    – wallyk
    Jul 4, 2014 at 8:47

2 Answers 2


You would be far better off building a roof type structure over the window well that is well above the window well and projects far enough out around the edges of the well that rain water does not enter the well.

Trying to jury rig a scheme to keep an existing lid open "just enough" sounds like a recipe waiting for disaster. Either it will be left closed with the AC unit on and it will overheat and kill itself due to inadequate air flow. Or the lid will be left open an flood of water will enter the well and try flooding through the AC unit creating a potential safety hazard.

  • In the end I got a built a frame for a window unit so it could be secured in the odd-shaped casement window in another part of the room. This took some work to secure, but it works well and looks pretty good. The frame distributes the weight nicely, and there are no airflow problems. Sep 10, 2014 at 2:07

I think I'd suggest looking for alternatives which don't involve that window well. Perhaps a ducted A/C would let you install the ducts through the wall above the sill (as you would a dryer's output).

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