It says that you vent it to the outside by using a hose.  One of the comments says that the exhaust venting hose should not be more than 5 feet long. 

You'd want one to vent to outside otherwise it's not a true air-conditoner.  The vent out pulls out the hot air and humidity in your trailer to the outside.

When I priced with a local RV dealer to have a roof air-conditioner put in, they priced me around $1,200. for the new unit, bracing, wiring & tax.  There's been a recent post on this within the last couple of pages and someone had a web-site for some roof units at some good prices. The other half is having someone install one for you.

I went with a portable unit and vented out the window.  I really didn't want to put a hole in the walls or back to the horse compartment.  In the next couple of months will be the best time to shop for them with the end of the season sales.

I shopped E-bay and was able to find the size and weight I wanted and it was cheaper even with shipping costs.  I do know Lowes, Menards, Big Lots, Shopko some Wal-Mart will have the units. 

When I was at Menards, a salesman helped me with what size I would need based on the size I told him my living quarters are. I needed 5,000 to 7000 btu. 

I knew where I wanted to put the air-conditioner to save space so was looking for a certain height. The unit sits partly under the table so I could run the hose under the table then beside the table to the window. I also wanted one that I could manage the weight myself and ended up with one around 55 lbs.  I do take it out when it's not the hot season.

I then went to a local glass & repair dealer.  I have one big window with two smaller windows below. They slide open so they put a hole in one window and added a sliding piece with seals that sit beside/behind the hole.  I do have an attachment piece I can leave in the window that I attach the hose to.  If I'm not using the unit, I can detach the hose and put the cover over it or I can take that attachment piece out and use the sliding piece to cover the hole.  Works nice.

The other thing I looked at was the wiring and with this unit, I can plug in with what I have.  I haven't had the chance to use it much but so far so good.  I was able to get everything done for around $400.00

I had to make a choice also. My trailer came with a window unit but it sat on a shelf into a place cut into the divider of the LQ and horse part. It blew hot air back into the horse part of the trailer and made it steamy back there.

http://img.photobucket.com/albums/v74/trfolks/Trailer/IMG_1244.jpg 

See the cut out space? Anyway, I use the back part sometimes for a guest room or my changing room and I didn't want it to be an oven. I have checked into portable air conditioners before and besides the fact, they are huge and heavy, they do need to vent somehow or you will blow hot air back into your LQ.

I couldn't justify the cost of the rooftop air conditioner. Plus I had several people tell me how they hated having the air blowing right on top of them in bed.

I took my trailer to a shop that builds interiors for horse trailers and had them professionally install my window unit into the gooseneck. It cost about $200 for the install (they also had to move my tire to the side of the trailer and weld a bracket). So the unit is protected from hail storms since it is under the gooseneck, I don't have to worry about ripping it off going under something too low and I can replace the unit when it poops out. Someone who is handy and has the right tools could probably do it themselves.

http://img.photobucket.com/albums/v74/trfolks/AC.jpg

During a recent campout during HOT and HUMID weather, it was 69 degrees in my trailer  I was shivering when I took a shower! So I am very happy with the choice I made.