window ac unit vented air temp

[darkhollo]

I have a frigidaire 5000 btu window unit built into a box, wrapped in polystyrene insulation.. 245 CFM 6 inch inline fan in, same fan going out.

I ran it inside an open garage.. I know it won't cool the garage by cooling and venting into the same place.. just wanted to see if i could keep the thing running for an hour or so.

The exhaust temp on the air was 140 degree F!! What are others seeing? Is this cuz of the constant run time? That seems H - O - T ! It ran for an hour or two straight which I wouldn't think would be the case in my 6'x6'x8' room with a single 600w. Just trying to gauge the exhaust. Not sure I can / want to vent straight into the attic if it's that hot all the time.

-dh

 

[NorCalFor20]

yea i would like to know too i was going to build a box for mine.

 

[Sheeba]

yeah that sounds about right! You have to exhaust all that hot air somewhere... if the A/C stays really hot it will run 24/7 and will hardly cool your room at all...

thats why they go in windows

 

[ChronicChemist]

So your saying you got a 600w in a box that has a 5000 btu AC unit built into it. How big is the box? The box has a 6 inch exhaust, and the AC unit just blows its exhaust into the room that the box is in. So the Air being exhausted by the AC unit is 140 degrees or the air exhausted out of the box? AC exhaust is going to be very hot, basically it heat the air outside more than it cools the air on the inside, so you need to get the exhaust from the AC into a different space, such as the attic, with attention to smell control. Also the AC unit can only cool so much air per each time the air is cycled through, and if your just exhausting all the air out of the box that was just cooled then that isnt going to help. I believe this may be basically along the lines of sealed room vs vented room.

 

[darkhollo]

Well the saga continues...

I have a 5'x5'x8' room, complete sealed. I have a window unit ac built into a box of it's own. The box is framed 2x4, then wrapped in 2" polystyrene insulation. Drain tub in the bottom of the box to catch the water with a line to dump into a bucket. I have a 6" inline fan blowing in the bottom (265 cfm) and the exact same model blowing out the top.

I have 4 foot of incoming insulated duct and 8 feet on the exhaust side. I can't seem to get this damn thing to cool. I mean it can't be rocket science. What type of clearance around the backside of the box do i need for this to work?

I also didn't realize it would be 140 degrees. I agree that the heat must go somewhere.. i just didn't realize it would be throwing off that kind of heat. I thought maybe 110 (well I actually didn't give it much thought.. but 140 still seems toasty)

Oh well, I'll keep trying, searching, reading.

-dh

 

[darkhollo]

Thanks for the tips.. I was heading in the same direction you are speaking of. I guess I just didn't pay enough respect to the design of the AC in hack #1. I will repeat my process with some testing and I think I will document it for ICmag this time. Find something that works and maybe others won't spent the days of testing, re configuring, more fans, more duct, shorter duct... etc etc.

Hopefully today or tomorrow I can hack something out.

-dh

 

[darkhollo]

Ok so I figured out my AC issue.

My ac sucks air in passively from the top and sides. There is a fan blowing air over the rear coils. I picture framed the front and rear (for hanging support) The framing isolates the rear of the ac from top/side area. My first design attempted to have the back as if it was hanging out of a window.. but the new design isolate the two area, caulking and metal taping them off from each other. I removed one fan and only have one blowing out of the rear chamber.

The intake is passive. The unit stayed on for 3 hours continuous and my exhaust temps were only 95F degrees, down from 140!!

I wanted to take pics, but after my initial build, add a fan, move the intake, move the duct, shorten the duct, . . . etc etc. I felt like it might not work again, so no pics. But this box is way smaller and way more efficient. Just one 6" 260 CFM for a 5000 BTU unit.

So moral of the story.. isolate the natural intake vents from the radiator/coil in the rear and you should be golden.

-dh