The roof AC in my 28 foot travel trailer in which I full time with my dog, died last year in the middle of a heatwave in the middle of July in east part of San Diego with temps over 100. Moving was not an option (fixing AC - long story - suffice it to say that the evap solution works so great the AC unit still needs replacing).
I removed one of the RV windows, built a stand and jammed up to the window the huge Bonaire Durango Window Evaporative Cooler
https://www.homedepot.com/p/Bonaire...PIPHorizontal2_rr-_-304156139-_-204679889-_-N I paid like $500 and it weights about 100 lbs, wouldn't fit into an SUV, had to get a neighbor to come and get it with a truck, I would have had it delivered to my site had I realized that. My neighbor upon seeing this beast told me that the heat must have fried my brains. The unit says will cool 1600 sq ft house. I figured if it would do that it can handle my small 28 foot trailer.
I used it all last summer and never took it down from the window because we never really got much of a winter this past year. I absolutely love LOVE LOVE this monstrasity. I know there is one guy who makes evap cooler for RV roofs but they're like $3K. Having lived many years in FL I do not miss the humidity and I quite dislike air conditioning plus the expense and waste of energy. I'm also forced to leave my dog unattended in the trailer and I'm always worried that a circuit will pop (used to happen during heatwaves when everyone sucks the AC power) or for whatever reason the electric goes down, then she would be stuck here with all doors/windows closed. With the evap cooler you at least leave the windows open and my circuit never pops, only use is a water pump and fan, I pull the plug on everything else to make sure to keep my usage down.
My trailer is of cheap paper, plastic, and styrofoam with fiberglass exterior coat variety, in the winter I can feel the air moving through it, it's a sieve. This evap cooler is a 1000% improvement, having a window open is what you need to keep the air circulating. I leave one window open at the other end of the trailer so the cool air needs to pass through the entire space. I read that what makes some of those room sized evap coolers not work is if they recirculate the interior air, turns hot and dry into hot and muggy, once humidity goes up it stops working. In my experience it's important to keep the air moving in and out and for my dry extreme heat conditions here this thing is absolutely perfect. The electric bill is smaller in the summer now than in the winter. Not only that it cool, in my opinion better than the AC, but the added moisture makes the interior so very pleasant. If I close my eyes I can pretend I'm feeling ocean breezes. It's true that when humidity reaches 30%+ loses its effect but it hardly gets like that around here. I swear by this thing. Of course this is not a solution if one is on the go unless someone handy would build a stand on the interior of the trailer and mount this cooler to the sidewall. The unit would stick out about 4 inches, not sure if that would be legal. I'm not going to bother with that because my plan is to put the trailer into storage. I've been full timing in this trailer for 5 years come this 4th of July. Day of Independence!
Recently I bought an old ecoline van, the trailer will get stashed in storage and I want to hit the road with the van. I plan to go to cooler regions but for business reasons will need to come and go to the current area so heat will still be an issue. Ironically, the AC in the van isn't working either. I'll probably get that fixed before hitting the road. I'm thinking about scaling down this beast into yet another over sized unit, like one maybe meant for 600 sq ft and figure out a way to make it work in a van, even if it does take some real estate.
One thing I don't really know is how much water it would use. The Durango is hooked up directly to outside faucet and taps what it needs, of course it's very big but I have no idea how much it uses, not enough to make a notice on the water bill. In the van of course I'd have to carry the water but I would likely only need it for brief time when stopping back into the hot areas, couple of hours here and there, I could get bag of ice for that time and I'm looking at different types of fans. I saw the home made evap cooler unit and one thing I like about it is that you can not only customize it to fit your space but you can do more than one fan and could run each fan on a separate power supply to minimize risk of failure. On absolutely too hot days, the dog will need to go to daycare, groomer, or I can hire dog walker (there's a bunch of them around) for a couple of hours since that is what I typically need when I have to attend some meetings, expensive, but you gotta do what you gotta do.
