when camping in colder weather wifey likes her heat, she also does a lot of cooking on the stove and uses the oven occasionally. We experience a lot of condensation on the windows to the point the sills are full of water. Usually we are 4-5 people +50lb dog which produces a lot of water just from breathing.at first we noticed the back corners of the slide where wet and the walls felt like they where sweating towards the bottom where the mattress hits the wall. We initially thought something was leaking from outside, but after testing with a hose it doesn't seem to be coming from outside.This past weekend, it was only the wife, myself and the dog. We bought a 30 pint GE dehumidifier and ran it the first night which was ~45-50F. we noticed in the morning the windows where almost 100% clear and the slide walls felt dry! awesome...problem solved...I thought!That morning it had rained a bit and was cool during the day. at night it dropped to about 32F, the heat was running pretty much non stop all night. the next morning we had some condensation on the windows, still much better than without the dehumidifier. However the walls still felt a little damp in the rear slide and if you ran your fingers along the edge of the rear slide wall, they came up wet.I also bought a cheap humidity monitor which said the humidity was at 39% in the mornings. so I think that's pretty good, even our hands felt dry in the morning.I just don't know what to check next, the moisture in the rear slide is unacceptable and you can already sense a slight mildew odor.We love everything about the 250rs but the moisture problem in the rear slide, we don't want the trailer to go to crap, but don't know what else to try? here is a pic of the rear slide for those not familiar with them:

Suggestions from a hybrid owner. 1) Cook outside as much as you can. We never cook inside and don't have or want an oven2) open a roof vent, turn on the Fan-tastic fan and crack a window for air circulation. 3) keep the inside cooler. I can camp down to freezing with just a 1500 Watt electric heater. Low to mid 60s is comfy.

You might need to try some way to insulate the walls from the outside. Some kind of wrap type insulating feature. Basically, you need to keep the walls in the slide out warmer so humidity doesn't condense on them.

bid_time wrote:You might need to try some way to insulate the walls from the outside. Some kind of wrap type insulating feature. Basically, you need to keep the walls in the slide out warmer so humidity doesn't condense on them.Yes, I've considered that, but there is no easy way and I would cover the windows, seems like a PIA, If I can't have a $25k trailer not rot the slides out from the inside, I would just assume sell it and buy a trailer without slides.But before it comes to that I'd like to hear from people with the same trailer and find out if they have had this problem and if they where able to solve it.

Well, ChooChooMan beat me to it....this could be posted on the hybrid side of RVNet except that it's not a true hybrid, it's an expandable with some of the same issues. Forget boiling water inside later in the day. Air circulation is absolutely crucial and if you need to add a portable fan, so be it. Opening a window a bit has always been one of the suggestions for hybrids, but DH had no thought of letting that happen when he was trying to get warm, not let cold air in. Something to think about, though. The problem comes with the fact that the bed area is just sort of hanging out there and not sealed in the main part of the trailer...the temp difference causes condensation and there ya go. One thing we did with our hybrid and while it was not a 100% fix, it did help keep the mattress bottom dry - if you haven't checked yours you need to do so as it's likely damp - is to add a product called HyperVent, I think. It's used in boating applications a lot so if I'm wrong about the name, you should be able to find it. It lifts the mattress off the deck about an inch and allows a bit of air flow. It's not inexpensive....we bought it in '07 and for the queen size bed was about $106, so I'm sure it's higher now. Again, it is not a complete fix, but does lift the mattress above the bottom moisture.Our ROO had heated mattresses, which were wonderfully warm, but added to the temp difference. You could try a heated mattress pad or electric blanket for your DW, but the difference is still there. I have seen folks attach a heavy vinyl fabric along the edge of the slide and drops to the ground level, keeping out some of the cold in that area. Do not know how successful it was, but maybe worth a try.So the main things are no cooking on the stovetop with water based items in the evening, turn on the vent fan for as long as possible and with a window just slightly cracked, do your best to keep the mattress bottom dry and check it every morning - just wiping the deck dry with a towel will take care of the moisture on the deck, but we had some times before the HyperVent when we set a few cans of food under the mattress to allow it to dry out. One other suggestion that's similar to the Pop Up Gizmos we used with the hybrid is to make a stop at HD or Lowe's and check into a sheet of reflectix that could be temporarily attached to the top of the slide to insulate a bit more. The PUGS are made from a similar product and work wonders. Doubt that you should try to close up the slide with it attached, but maybe you could come up with a way to fold it or roll it up for storage.I doubt that you're doing permanent damage to the trailer, but until you have this under more control, suggest you wipe down the walls and windows in that area daily. FWIW, I have heard that many folks with 5ers have this problem if there is not enough space between the bed and the floor - again, temp difference. Good luck.

We have the same slide in our model. The only time we had that problem was when heating the unit when the outside temp. was in the 20's. Only the back wall was affected. Haven't solved it, but think a dehumidifier is a good choice. .

Outback 250rs Rear Slid Condensation Issues | Good Sam Community

katoom400
Explorer
Oct 15, 2014
fatboy66 wrote:
Get yourself a dehumidifier. That will remove a lot of that moisture.

If you read my original post, you will see that we did, and it was definitely better, but not solved.

I'm starting to think it is because the slide is so deep and shallow that the air we breathing out just stays down in the end and produces the condensation, you can see it on the back window where the pillow was touching the glass, and you could feel it on the in between the walls and the mattress on the back wall and the rear of the side walls.

thinking I need some kind of fan to get that air out of there so it can be dried by the dehumidifier.

according the hydrometer it was 39% humidity in the trailer in the morning, that should be good enough, as even our hands felt dry.
fatboy66
Explorer
Oct 14, 2014
Get yourself a dehumidifier. That will remove a lot of that moisture.
PAThwacker
Explorer
Oct 14, 2014
Condensation occurs in all campers whenever the interior temp is warmer than the exterior. Imagine a glass of water with ice. Water droplets form on the exterior of the glass. Cold/warm barrier area.

To cure it: leave a window open and fan spinning.
Thom02099
Explorer II
Oct 14, 2014
We have a 2007 Keystone Outback 25RSS, essentially the same trailer with a side slide as well. We've had no problems at all. we leave an overhead vent open all the time, and use the propane fired heater.

Part of the problem could be the relative humidity of your geographical location. We are camping in the Rockies, foothills, and high plains, with low relative humidity, since we are semi-arid. We've also camped with temps as low as the upper teens-low 20s. Cooking inside is not an issue at all, we've never had the windows fog over or sweat, nor any problems with condensation in the rear slide out, and we've camped at elevations locally ranging from 5000-10000 feet.

Our relative humidity during the day is usually single digits during the summer days, rarely over 30% during the day; nighttime does get higher, but nothing near what you normally get back east. We've also camped in pouring rain and snow and still have not had windows fog up or sweat.

Might want to check out the relative humidity (smart phone apps for that, like through WeatherBug or Wunderground) for the times when this happens. My guess is that the relative humidity is...relatively high!
westend
Explorer
Oct 14, 2014
Your choices would be to insulate the walls, floor, and ceiling of that area better or direct warm air against those parts to bring the temperatures up. One easy thing to do might be to raise the mattress up a few inches on blocks or strips during the day so air could circulate underneath it.
Jayco254
Explorer
Oct 14, 2014
I have a rear slide too but it's not just the slide out that sweats, all the windows sweat, the only way I know how too stop it is to cool down the inside and let some air flow through it by opening a few windows and vents then turn on how ever many outside fans you have.
katoom400
Explorer
Oct 14, 2014
campincandice wrote:
Electric heaters instead of propane will also cut condensation!

I keep hearing this statement, but in my head I can't imagine why since the propane RV furnace is vented outside so it should not be adding moisture to the air like the stove/oven? am I thinking about this wrong?

I also believe that perhaps the shape of the slide is contributing to the problem as it basically a long rectangle sticking out of the back.

Our heads are at the back, so we are exhausting all of that moisture to the area least likely to get circulation, and by the time I'm done breathing out 10-12 beers there could be a lot of condensation in the back area...lol
campincandice
Explorer
Oct 14, 2014
Electric heaters instead of propane will also cut condensation!
kodiakcanuck
Explorer
Oct 14, 2014
I have pretty much the same rear slide unit and do experience condensation on the back walls and the edge of the slideout as you noted. I really don't think there is much you can do aside from all the other suggestions. I try to leave a window cracked and a van running and avoid boiling water inside. If I do cook inside, I make sure to leave the exhaust hood fan running for a long time. We havent used a dehumidifier but I suspect that will help a lot.

I just wipe everything down with a towel in the morning and move on.

Good luck.
Speedogomer
Explorer
Oct 14, 2014
I haven't really had that problem myself. The windows are damp in the morning, but I wouldn't call it excessive. Just getting air moving during the day (fan on or window open) drys it out fast for us.

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