Hello, can I vent a portable 10,000 btu air conditioner into my crawl space? I have casement windows, both horizontal and vertical crank-out all through my house so can't use a window to vent the exhaust. My crawl space is completely open the entire length and width of my house. This crawl space has 9 or 10 rectangle air vents to the outside, 2 on each wall. I can stand up in it bewteen the floor joists so plenty of space. I have good lighting down there and have some storage of empty boxes and the like. On the one side of the crawl space, I have my house heating system which suspends from the floor joist. I am not in a flood plain. My livingroom, dining and kitchen area is all center of the house living with doors and windows off the living room end and the kitchen end area. There is very little outside wall to vent wall from living room end and of course no proper windows.(My bedrooms and baths are all on the outside walls.) Where I want to vent in my living room is about 25' from the suspended heating unit inside crawl space. Do I need this much distance from say a pilot light? Is it possible to vent this way? Thanks.

 

Search google for:

vent portable AC casement windows

There are at least 3 hits.

 

The answer to your question would be no.
The crawlspace would heat up in very short order to where the air conditioner would not work.

For it to work you would need to provide forced ventilation of the crawlspace.
An exhaust fan that gives you 700 cfm would be the size you need.
It would be easier to figure out how to install the a/c in your casement window.

 

I assume this is a single hose AC. You could vent down into the crawl space especially if the vents are open. The crawlspace will be heated by the AC exhaust and you will probably have higher humidity down there as many units evaporate the condensate and blow it out in the exhaust. Also, single hose units are very inefficient. Because they only have one hose blowing out that air has to get into the house somehow. What ends up happening is air is sucked in through every crack and crevice bringing outside air into the home to replace what you're blowing into the crawlspace. So while the actual AC unit may be half way efficient the way it operates makes it very inefficient. So yes, you could exhaust your portable AC into the crawlspace. You probably won't get the cooling you expect but it should work to some extent.

If you have a two hose unit I would not vent it to the crawl space. While the AC operates much more efficiently you'd just recirculate the hot humid air in the crawl space which will hurt it's efficiency not to mention what it would do for anything stored down there. At least with a single hose unit you're always blowing air into the crawl space which would go out the foundation vents so it would only get moderately warm and humid. Running the same air in a circle would make it hotter and more humid on each pass through the AC until it reaches a point where it really can't work anymore.

 

If it is one hose best to return it and look for a two hose. The one hose blows your cooled air outside and hot outside air has to come in to replace the air blown out. A two hose uses outside air to cool the condense so it cools better. Ideally no warm air from outside constantly diluting the cool air.

Build a Plexiglass covered wood frame to fit in an open window and cut a hole in the Plexiglass for the vent.

 

Ill add my 2 cents. Everyone has talked about heat which I 100% agree with. Id worry about condensation from the hot exhaust and the cool temps of the crawl.

 

One more vote for no - adding moisture to a crawl space is dang near an absolute no.

 

Ok. Thanks Everyone. Wasn't sure if it would work proper. I have decided against it. I do understand your point with me but was wondering how they are efficient, in say, Arizona where they are getting the inside air to blow back out into 110 degree heat in summer? Usually, those homes are fairly air tight with all windows closed or sealed, all doors closed tightly, etc. Where does the inside air come from to blow back out through the hose to the outside? Thanks. BTW, I am in a Northern state and would only need AC no more than a month in summer, if that.

 

I have a single hose that I use in my toy car garage. On a hot, humid NC day it does almost nothing. For all the hot air it blows out the hose just as much hot, humid air get's sucked into the garage. I used aluminum trim stock to make a box (plenum) over the intake and ran 6" duct outside converting it to a two hose model. It's a night and day difference and amazing how much better it works at cooling the space.