Wall AC Unit Enclosure

[cpl5571]

Hello,

I have a 15 x 30 double-wall construction building in my backyard. For cooling/ventilation I have a thru-the wall AC unit. In order to minimize the sound escaping through the unit I built an enclosure around the unit on the outside of the building. I have attached an image which hopefully gives a good idea of what it is (it is not exactly to scale, but it is close enough). It is sort of like a half of a doghouse.

All walls are insulated using standard R-13 wall insulation and the ceiling has R-19. It is built with 2 x 4 stud framing with 2 layers of 5/8" sheetrock and wood siding.

As far as minimizing the sound, I am happy with that. My problem is that hot air accumulates within the enclosure, which I believe is making the AC ineffective (something is making it ineffective as there is barely any cool air felt coming out of the unit).

My question is - what is the best way to eliminate the accumalated hot air? I was thinking of either putting in an exhaust fan where the enclosure opening is, or cutting an opening on the other side of the enclosure in order to get some air flow. BTW, this room is used for rehearsal, so my main concern is keeping sound from getting outside, and the sound of the AC inside is not so much a concern.

Any thoughts would be appreciated.

Thanks,

Craig

[rod gervais]

Unfortunately - what solves your HVAC problem - opens up your noise problem.

Thru - the wall AC units require free fresh air - and that is what this is not getting.

You need to open up your shed to allow fresh air to enter and circulate.

Another option would be to move the AC unit to the outside wall of the shed and develope a lined plenum inside of the shed to handle the noise problem......... you will also need (then) a fan to pull the return air out of the space and into the thru the wall unit - the unit isn't made to handle the back pressure that this type of a system will create.

Another option (simplar to the above) is an idea that Steve mentioned to me - and that would be to super insulate the shed and turn it into a chiller room - and then draw the cold air out of there into your space.

Any of these would work - the last probably being one of the better ideas.

Rod

[knightfly]

Heres a link to the discussion in question... Steve

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=644

[cpl5571]

If I did the Basic Cheapo A/C method, it is not necessary to have a blower for the exhaust fan? How does the air get out , then? Is it just due the fact that as the new cool air gets blown in, some air needs to get pushed out to make room for it?

Thanks,

Craig

[knightfly]

Right - if there's an exit, the air won't build up any more pressure than that required to force air out the exhaust port.

If your isolation requirements are high, Rod points out that having the fan on the outlet of the room would cause sound to have to buck the air flow and should quiet things by a few dB - my original thought was to have the blower on the inlet side, which would slightly pressurize the studio so that when doors are opened it doesn't suck in dust - this is standard clean-room procedure to have a positively pressurized room, but clean rooms generally aren't sound rooms.

I'm still contemplating a good way to maintain isolation between inner and outer leaves for this method - for small booths, I'm looking at ABS sewer pipe for ducts with a booster fan inline and rubber couplers in the walls. That's about as far as I've gotten though, too many 'gators in the pond these days... Steve

[cpl5571]

First of all, thanks for the responses and the great ideas. I ended up installing a basic attic ventilation fan (1050 cfm, $40.00 at Lowe's) in the enclosure's opening. Fortunately I had a 16" wide opening there, so the fan and the auto-open louvre ($20.00) fit in very easily.

This did the trick! On Sunday I practiced with my bands for about a total of 6 hours. At one point there were 7 people in the room (it is 15 ft. x 20 ft.) and it stayed cool all day. The AC unit has a fresh air intake, and nobody passed out, either.

This room is mainly used for band rehearsal's at this point, so this solution works fine for me. If I was concerned about the sound of the AC inside the room for doing recording, or I was starting from scratch, then I would probably look into the chiller room idea discussed aboved.

Craig

[ThomasMaloney]

Great to hear that you've managed to find a good solution for the air conditioning problem you've got here. I was actually going to suggest some sort of portable fan that you could have put in when you really need the air inside the studio to be circulated around - I should think that it would easy enough to find a fan unit that would be virtually quiet as long as it's well maintained and oiled around the moving bits right?


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[Soundman2020]

Great to hear that you've managed to find a good solution for the air conditioning problem you've got here. I was actually going to suggest some sort of portable fan that you could have put in when you really need the air inside the studio to be circulated around - I should think that it would easy enough to find a fan unit that would be virtually quiet as long as it's well maintained and oiled around the moving bits right?

Thomas, you are responding to a thread that is nore than thirteen years old. The original poster hasn't even visited the forum since his last post. And you are committing the same error he did, way back then:

Please read the forum rules for posting (click here). You seem to be missing something.

- Stuart -