Roof Top Terrace AC Unit - Acceptable Location?


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Old 01-31-12, 10:01 PM
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Roof Top Terrace AC Unit - Acceptable Location?

I need advice - Can a AC unit be installed on a roof top terrace that is more like a attic dormer room that is open to the outside? The space has walls on 3 sides and the forth wall (12' wide) is open to the outside with a railing. The space is 12' wide x 6' deep x 7' tall with a ceiling/roof above. There is limited access to this space and the space would not be needed for anything else.
Can a AC unit be installed in this space and get the proper ventilation? Can 2 AC units be installed in this space and get the proper ventilation? How much space would be needed around the units?
Thanks for the advice.
 
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Old 01-31-12, 10:19 PM
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They should not really be put there, but you would probably be ok. The A/C unit should have 18" of space around it on all sides.

Depending on the size of the a/c units it should work.

You want to have as much open space as possible from the top of the unit.
 
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Old 02-01-12, 09:59 AM
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Yes, many many California city single family home has their AC unit on the roof. I like it that way, since you won't hear the noise of the unit.
 
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Old 02-01-12, 10:16 AM
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Hold on a sec Pro's...

I remember almost everyone being against putting a 3 sided enclosure around an A/C in a thread a while back...even when the guy said he'd build the roof 7ft tall and vent it and leave 2 ft around the sides.

Won't it tend to just recirculated the hot air back down to the coils? Esp with 2 units?
 
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Old 02-01-12, 04:11 PM
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yes, it will that is why is started out saying
They should not really be put there
can it be done? Yes. Will it work all that great? Probably not.

If this is a townehouse or condo where there is no other place to put it, then you dont have much choice. The op being in Chicago, it is not going to see a great deal of use to begin with.
 
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Old 02-01-12, 04:36 PM
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The space is described as having a wall on three sides and the fourth wall with a railing and a roof overhead.
To me it sounds like a mostly enclosed room with an opening at one end.

The only type of a/c unit that I would suggest installing is possibly a mini split that has a forward facing condenser fan placed near the outside edge and blowing away from the space.
Any condensing unit that blows upwards may have a shortened lifespan.
 
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Old 02-01-12, 04:41 PM
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I did see something a while back about units that exhaust out the sides as opposed to the top?
 
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Old 02-01-12, 04:51 PM
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Something like this maybe?


Image courtesy of ac-review.com
 
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Old 02-01-12, 05:13 PM
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No...It looked more like a typical unit...just that the airflow was reversed. I know what a mini-split looks like.
 
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Old 02-02-12, 09:07 AM
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Come to West LA, California, you will see hundreds of those units on top of the roof. They build a flat platform on top of the roof to seat the unit. all sides clear.
 
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Old 02-02-12, 09:21 AM
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True...I have a package unit on my roof....as does almost everyone that doesn't have tile roofs. Even some of those have a section of shingles just for access to the unit.

But those are all unobstructed by walls or roofs.
 
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Old 02-03-12, 11:44 PM
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Thanks for the response. If it is 95 out the unit is only going to pull in 95 degree air at a minimum to cool the coil. I was hoping there would be enough air circulation with a breeze and with the hot exhaust air rising to keep the hotter air moving up and away.
To hvactechfw - Do you know the typical temp of the hot air being blown off of the coils? If you have an idea of this let me know.
I will have to do some decision making on this one.
Thanks again.
 
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Old 02-03-12, 11:50 PM
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typically 20F higher than the ambient temp with CLEAN coils
 
 

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