Window AC in a box

[wlivesey]

What would it take, in terms of ventilation/airflow, to mount a 5000 BTU window air conditioner in a box and still have it cool effectively?

Without getting into too much detail about my build, I need to mount a 5000 BTU window AC unit in a box that is about 6 inches bigger than the AC in all directions. I know I need to separate the intake from the exhaust to prevent hot exhaust air from getting sucked into the intake. I know I will need to use a fans/blowers to assist the intake an exhaust. I'm curios how much air movement, in terms of CFM, would be sufficient. Some say it can't be done - I disagree... There are just too many portable AC units on the market...

Has any one done this??? I'm pretty sure I've seen all the teardrop examples. They typically have the exhaust side exposed. This really isn't an option for me.

Come on guys and gals - lets get creative!!!

[Cliffmeister2000]

Mine is tighter than that. I have 3" clearance for the exhaust, and a 3" x 12" duct to the side of my Weekender. I have the duct angled up so any water that gets in will roll back out. I have a marine louvered thing from eBay for the exhaust grill.

I had originally put a filter in the exhaust to prevent bees and such from nesting there, but the filter restricted the airflow too much. Now I plan to make a cover for when it's not in use.

I don't have a photo of it complete, but this shows it.

[wlivesey]

Judging from your pictures, it looks like separating the intake from the exhaust is the most important part. It give me hope - I was growing concerned that I might be in trouble.

[Arne]

not sure why you would need an additonal fan. If you separate the intake and exhaust of the cool air and the return with a manifold, that should suffice.

And, yes, you should keep the warm air from being sucked back into the intake on the condensor (back end).

[wlivesey]

not sure why you would need an additonal fan. If you separate the intake and exhaust of the cool air and the return with a manifold, that should suffice.

And, yes, you should keep the warm air from being sucked back into the intake on the condensor (back end).

Googling had led me to that belief. Indeed...

[Larwyn]

I just allowed the area (in square inches) of intake through the floor to be the same as the as the total area of the vents in the side and top of the AC cabinet. The exhaust on mine is unrestricted. I have no extra fans to assist that portion. but it does seem to actually cool better if I partially open the fantastic vent and put it's fan on low (blowing out). It also seems to help the cooling a bit to slightly open the door windows. My design does allow for a bit of the cool inside air to be mixed with the outside air intake the AC unit.

A side benefit is that the Fantastic Vent can draw air from the vents under the floor of the trailer at the foot of the bed in addition to the air form the side windows to help cool the cabin when there is no shore or generator power to run the AC unit. Drawing air along most of the length of the mattress is a great advantage over only the side windows.

It works very well for me.

[WesGrimes]

...it does seem to actually cool better if I partially open the fantastic vent and put it's fan on low (blowing out). It also seems to help the cooling a bit to slightly open the door windows.

I wonder why this would be. I am sure this is some kind of air pressure issue.

[Woodbutcher]

I have my AC exhaust into my tongue box. I just prop the lid up and rest it on the latches. So the opening is about 2" X 40". The grill in the picture is the AC inlet. There is a wooden deflector sending the cold AC straight up out another vent in the top of the headboard, So no cold air blows on me. I find that cracking the ceiling vent gives be make up air. Works real well.





here was a test during my build, The paper streamers show the cold air blowing out the headboard vent.

[Miriam C.]

I have lots of ways to exhaust the air from mine but have an extra fan to help it along. We get some pretty hot and humid days here so it helps. I find the air around the air conditioner gets pretty hot with out it. It is noisy so I try to not use it often.

[wlivesey]

I have lots of ways to exhaust the air from mine but have an extra fan to help it along. We get some pretty hot and humid days here so it helps. I find the air around the air conditioner gets pretty hot with out it. It is noisy so I try to not use it often.

Problem Solved. I did almost exactly what you did, Miriam. I have less room behind the AC and I added a second fan. Yes, its kind of loud, but it works perfectly. It's also very well insulated (with the bubble wrap foil stuff) so the noise doesn't seem to bad inside. Thanks for everyones input...

This is the wall that separates the intake vents from the exhaust vents. I sealed this area with caulking and then insulated with the foil/bubble wrap insulation. Sorry, no pics of that...


These are the two exhaust fans the blow hot air out into the wheel well. They are both wired to a to a switch that the AC plugs into. This prevents the AC from running without the fans being on.


I spotted this paint pan at Home Depot. With a few large holes drill in the bottom of the pan, I think it will make a great vent cover for under the trailer. No body will ever see it...

[caseydog]

I built a box around the backside of my unit. It is the same dimensions as the unit, and about four inches deep.

Then, I added a tall louvered vent to allow cool air into the galley, and another higher-capacity vent to allow hot air out of the box. The condenser fan is strong enough to blow the hot air out without help from additional fans.

If you wanted this to be portable, you could just put the same setup as mine inside a bigger box. I still don't think you would need any additional fans -- just enough vent area to allow the condenser fan to "breath" properly.




CD

[starleen2]

Problem Solved. I did almost exactly what you did, Miriam. I have less room behind the AC and I added a second fan. Yes, its kind of loud, but it works perfectly. It's also very well insulated (with the bubble wrap foil stuff) so the noise doesn't seem to bad inside.

HUmmmm. . . 100 degree Texas heat or a little fan noise???
Looks like you'll be camping cooler in the future