help with the different workings of a window AC unit

[universalexports]

well I am in the planning phase of installing AC in my camper, I am basically going to build a dresser in the rear of the camper under the rear window with the AC on top, and want to make sure I understand how the unit works, from what I understand, these are the basics

the side vents bring in ambient air (to cool something?) this is the intake and is usually located outside when mounted in a window,

the front piece that has a filter, brings in "room air" and filters it, cools it, and blows it into the room.

the Back of the AC unit discharges the hot air. is this correct?

from my understanding an AC unit will only cool air 20 degrees below ambient(this is the temp of the air brought in through the sides?? correct?)

if this is correct, I plan to make my intakes (side vents) pull air from as close to the floor as possible to bring in the cooler air, I plan to add filters there as well. the vents will be larger to compensate for air flow restriction from ducting.

ideas? input? snide remarks?

[bigbill]

an air conditioner has two air flow systems. One draws air in the rear sides blows it across the coils in the rear to extract the heat from the refrigerant and discharges out the rear, the other pulls air in the front through the filter blows it over the evaporator which absorbs the heat from the air into the compressed refrigerant and blows cool air out the top vents. Normal cooling across the evaporator is 20 degrees but as the trailer cools the ambient air temp going across the evaporator is lower so if you have the proper size unit for the heat load you will cool the trailer down to the temp you desire. Two large of a unit you will get cold but the air will remain humid, to small of a unit and it won't be able to drop the temp to the level you desire. This is a super simplified explanation but I hope it helps. For an example a house on a 100 degree day if the air is sized right can be cooled to the low 70s with no problem which is 30 degrees lower than the outside air. hope this helps. If you are going to mount the ac unit inside the trailer in a cabinet/box you want to insulate the entire box top ,sides, and bottom from the window mount position back and seal at the window position to keep the hot air from the back from entering the trailer, then you must provide enough intake and exhaust air to properly cool the condenser that normally would be outside the window. This would be exterior air for the rear area.

[universalexports]

OK, thanks I think I understand everyhting I need to know.

[boandsusan]

We`ve experimented several different ways of installing a window ac. The best we found is installing, up high, in a closet. Sealed shelf above, sealed shelf below and 2 sealed divider walls. One divider wall, just behind the front of the ac and the other between the side vents and the rear. Imagine dividing an ac into 3 sections. Front section draws preconditioned air from the inside of the cabin as well as blowing out cold air to the cabin, middle section draws preconditioned air from outside the cabinet via holes in each side of the cabinet, rear lets hot are vent directly to the out side. We were lucky in that the closet we chose wasn`t but a couple of inches deeper than the ac unit. Had it been deeper we would have used a fan in the space behind the ac to draw the heat to the exterior. This method is working much better than we ever expected it truly freezes us out. It can be 96 degrees and with the door/windows closed and the ceiling vent open a crack, we HAVE to turn it to low cool after about 15 mins

[universalexports]

so the front and sides need to draw air from inside the camper, and the rear needs to exit the hot air out of the camper, right?

[lopo]

Is it possible to post a pic of these walls, Susan? What did you build the "walls" out of? How big are the holes you cut in the sides of the closet? And do you still think I'll need 8,000 BTU to cool Ms. Frolic? I don't want to get one so big that it doesn't dehumidify.

I set up the portable in there with the vent hose stuck in the hole for the stove hood fan and the hose puts out so much heat that it defeats the cooling. It might work in the big closet but it would have to be pushed to the rear, not using the vent hose, and a new vent cut, but then it wouldn't be flush with the front of the door, but stuck back in the closet.. I think I want to stick with a window unit - someplace, probably below the fridge which is low, I know, but I'm not up to, skill wise, building a separate cabinet for it in one of the upper sides window areas.