I have a central air-conditioning system in my rented flat. There is on massive machine on my balcony which blows out hot air when the air-conditioning is in use. The hot air is so powerful that it can hit you in the face from 2 meters away. I needed for some reason to block the hot air from blowing into the balcony so I put a wooden board in front of it and on the right hand side. Its only heat outlet therefore is on the left hand side. So to draw it out for you the machine is mounted on the wall. About 4 inches to the right there is a wooden board. About 8 inches in front of where it blows the hot air there is another board. To its left there is open air. The boards are getting very hot when the air-conditioning is on.

Will the air-conditioning break because it is too hot and the air isnt finding the left path to escape?

Is there something I can put in front of the machine to direct the blown air to the left and not straight at the boards?

  • Perhaps I could use a fan to blow all the hot air to the left. – yehuda Sep 28 '12 at 13:14

It's pretty hard to say without knowing more. The general idea is that the fan that's blowing hot air at you is supposed to be drawing cool air through a series of fins. The fins are full of hot liquid, and the cool air blowing through the fins draws heat from that hot liquid. Then it exhausts that now heated air.

So it should be drawing in ambient ("normal") air and exhausting heated air. As a broad generalization, exhaust air is noticeably warm, but not so hot that you can't stand it on your skin. One situation that can occur is the intake and exhaust air can be so close together, or be in such an enclosed/confined area that the heated exhaust air gets pulled in as intake air, gets heated again, and exhausted as even hotter air. And then pulled in and heated again, etc. This condition makes the unit very inefficient, and if it's bad enough, it can even be dangerous.

It's a matter of degree, so if the discharge air at your unit is so hot that you can't stand it, then there's probably a fair measure of this unwanted exhaust/intake air recirculation going on with your unit.

I said all that to say this: You're fine to deflect the hot discharge air in any way that you wish, as long as you don't cause (or worsen) a case of exhaust/intake air recirculation.

  • Can it break my air con or will it just work less effecinently? – yehuda Sep 28 '12 at 13:45
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    It all depends on how bad the recirculation issue is. My guess is that you can probably evaluate the situation and set it up to deflect the air in such a way that the situation is actually improved. FWIW, the recirculation problem has to be pretty bad before it'll damage the unit. – Bob Sep 28 '12 at 13:54
  • It is bad, it is boxed in from in front and on the right with about 8 inches to go. The left side is totally open though. Will a fan be strong enough do you think – yehuda Sep 28 '12 at 13:57
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    If I'm visualizing correctly, the cold air is pulled in at the bottom, the hot air comes out up top. If so, can you mount the board/deflector "midway up" so that cold air can still be pulled in from the front, but the hot air is forced off to the left? That will prevent the hot air from being drawn back in.... – Bob Sep 28 '12 at 13:59

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The AC condensing unit takes cold,40F low pressure refrigerant vapor and raises its temp/pressure such that is 30F above the outdoor air temperature in comparison, this allows for heat transferal, thus condensing of the refrigerant vapor to a liquid by rejecting heat outdoors, the refrigerant liquid is then evaporated to remove heat which is then rejected outdoors. You are making the condensing unit rebreathe its own hot air, not allowing it to breathe in the cooler outdoor air that allows heat transferal, this forces the condensing unit to pump the refrigerant to maybe 60F above ambient outdoors when 30 F works if not smothering the unit recycling its own hot air, this allows for little heat transferal as you require a temperature differential for any heat transfer, the lower the diferential, the lower the heat transfer.

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