Trying to install a multi-zone mini-split heat pump system in a small condo that does not have any accessible outdoor space* for condenser unit, however in the region jalousie windows are common and there are two floor level (total area 4'H x 8'W) jalousie windows in the living room.

Would it be possible to build a sealed and insulated box against the jalousie windows to house the condenser of the system? Ambient high temperatures for the region are 80-90F daytime, and the window it would located against would be NW facing.

*no it's not possible to hang it out a window, install it on a roof or place it anywhere outside.

  • condenser is bloving lots of hot air...where will it go
    – Traveler
    Jul 23, 2023 at 4:42
  • outlet would be situated directly facing one of the two jalousie windows, so it would vent outside, could add a fan/blower between outlet and window to increase airflow if needed Jul 23, 2023 at 5:11
  • why can you not used or repair the AC unit provided in the condo?
    – RMDman
    Jul 23, 2023 at 12:52
  • @RMDman what did i say that would make you think there was one? there isn't. Jul 23, 2023 at 18:48
  • @JaredZimmerman, Because trying to live in a housing unit where outside temps are 80 to 90 without AC is ludicrous.
    – RMDman
    Jul 23, 2023 at 19:20

2 Answers 2


Would it be physically possible? Sure. It might be a bit tricky but it could be engineered to work.

Would it meet local code? Almost certainly not. You didn't tell us where you are, but I can't think of a single municipality around here where that is possible.

There are also in-window heat pump units. They look like window AC units.

  • Will check code compliance on this. I assume the in-window units are visible from the outside, or protrude out of the building, this is not possible in our situation. Jul 23, 2023 at 5:09
  • @JaredZimmerman -- why wouldn't replacing a jalousie window with an in-window unit work? Some crazy local requirement that air conditioner units not be visible from the street? Jul 23, 2023 at 5:11
  • @ThreePhaseEel building requirements, not county requirements, but yes. Jul 23, 2023 at 5:24
  • Do you want heat or just A/C? If you just want A/C a portable two tube unit should be pretty easy to make work with this setup, and they're OK.
    – KMJ
    Jul 23, 2023 at 6:40
  • @KMJ only cooling is absolutely necessary, but it would need to be 3-4 zones Jul 23, 2023 at 8:12

I don't see a problem with the idea airflow-wise. You'd need to build a "box" for it, and duct that box really smartly so that it exhales through different panels than it inhales. Probably use foam insulation for that, but the important part is choosing a unit that lends itself to that.

You'd also want to insulate the box both thermally and for sound - outdoor units are LOUD.

I would build the box empty before committing to the mini-split, and leave it in the window for a month to see if any HOA people raise a ruckus.

  • Yes, definitely would need the box to be both thermally and sound insulated. separating intake and output venting would be somewhat possible since there are two windows (but adjacent) Would probably need to source a condenser that is both compact, and as quiet as possible, given the application of it. Not sure I understand your point about building the box first, since the whole enclosure is inside, and not visible outside. Jul 23, 2023 at 6:01
  • @Jared it wouldn't matter if they're separate windows but they'll need to be separate louvers so they don't "eat their own exhaust". The condensers are not compact nor quiet, but they're not horrible like old-style American ACs. Jul 23, 2023 at 6:20
  • @harper-reinstate-monica it's two 4'x4' jalousie windows that are part of one casement, they could be separated internally within the box, one handling intake one handling exhaust, but the windows can't be seperated outside, so the intake might pull in hot air from the exhaust depending on wind conditions. Jul 23, 2023 at 6:29
  • @Jared that's always a risk but hopefully if the wind is that strong it's also mixing in lots of cool air. Jul 23, 2023 at 17:27

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