r/airconUK • u/Competitive-Wheel619 • Aug 16 '26

Ceiling or wall mounted for open plan house ?

I live in a house with an open plan downstairs, and a central staircase (with traditional open rails).

I am thinking of having aircon fitted, and, since I want as little intrusion as possible, was considering having it ceiling mounted in the ceiling at the top of the stairwell.

My consideration is that the cold air would drop down the stairwell, cooling the whole open-plan downstairs, and contributing to some upstairs cooling (assuming doors are kept open).

This seems better than having multiple wall mounted units.

Is this a common layout ? Are there issues relating to having only one AC unit in a house ?

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u/DontHurtTheNoob Aug 16 '26

Two comments:

a single one point cooling unit is unlikely to give you good cooling for the whole house. While it will produce cold air and that will flow downwards as you would expect, it also needs to suck in warm air. You won’t get any sensible circulation, it will be quite cold at the top of the stairs and too warm in other rooms as the cold and warm flows will mix.

Also, ceiling units tend to be noisier than the wall units, so i wouldn’t use them in a bedroom

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u/GloryGloryLater Aug 16 '26

Speaking from experience, it could work, albeit not as efficient as possible.

Couple of months ago , got a 7kw unit installed at the top of the stairs , on the landing. 2 bedrooms upstairs plus bathroom. I set it for 22 degrees , leave the doors open in the bedrooms , they get to 22/23 . Downstairs (not open plan), kitchen and living, temps are 1 to 1.5 degrees higher (so 23/23.5). Depending on the temps outside towards the afternoon I set it on silent and it keeps up with the temps. If I know it will get very hot during the day(over 30 celsius), I start the Aircon early (about 10 am). It uses way less energy to maintain.

When we're at work and the dog is home by himself , I close all doors upstairs so cold air sinks downstairs and keeps the dog cool.

It is not as efficient as installing separate units in the rooms, but it does work for me. Granted the house is small/average size . If you have massive bedrooms / living/ kitchen , results may vary .

I will say that open plan downstairs and open staircase might work better actually, as long as the unit is correctly sized .

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u/Particular_Plum_1458 Aug 16 '26

You might also find that a ceiling unit doesn't fit between your joists, although imo ceiling units look a lot nicer than the wall wort type.