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Old 10-08-2018, 09:44 AM   #1
BamaRam
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Vent Condensation

Camping in low 40s temperatures. The front roof vent is sweating onto the bed, leaving a wet spot.

I checked around an the only other condensation I can find is on the door and windows frames.

Thinking of using foam sheathing cut to fit the vent hole to block warm air from collecting in the vent cavity.

Will this work?
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Old 10-08-2018, 11:10 AM   #2
jsmith948
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Best way to prevent a build up of condensation is to crack the vent open to allow the warm, moist air to escape.
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Old 10-08-2018, 12:37 PM   #3
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Ventilating is best, but over the bed you may want to get a vent Pillow. They are foam covered in fluffy material the exact size to place in a standard vent.
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Old 10-08-2018, 12:40 PM   #4
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^^ 2 Crack the vent open about 1/2" and open a window on the opposite end of the trailer. That will allow airflow through the rig and allow moisture to escape through the vent. You might also check behind the cushions on your dinette and the mattress on the beds where they are in contact with an outside wall. Chances are there's also moisture collecting in those areas. Be sure to pull all the cushions away from the outside walls so they can dry after you use the trailer in cooler weather where you see condensation forming on the windows and vents.
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Old 10-08-2018, 04:10 PM   #5
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Thanks to all for the ideas. I understand the concept of opening the vent. However the DW will have no part of it. Loose to much heat, she says.

During the summer (because it was very hot) I removed the vent in the bathroom over the tub and found the framing for the vent was not insulated or sealed. I used foam board and caulk to seal it all up. It sweats in this weather but not to the point of dripping. Maybe the front needs the same treatment.

The vent pillow looks interesting. Do they get moisture on them?
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Old 10-08-2018, 04:30 PM   #6
KeithInUpstateNY
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If you make your own vent cover you will want some kind of tab on it to get it back out. Expect some moisture to run off the top when you pull it out.

The vent pillows are available with fleece on all six sides, or with Reflectex on the top. Moisture will build on the top with either one, so you want to pull them during the day to dry out so you don't get mold or mildew.

Another solution is to take down the trim frame and cover it with clear plastic. Wrap it and tape the plastic to the outside where you won't see it once it is reinstalled. Foam tape around the four sides that meets flush with the sealing will keep moisture out. If you dry everything really well in the vent before you reinstall it it should be a once and done thing.
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Old 10-08-2018, 05:12 PM   #7
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Just get a dehumidifier a 30 pint unit keeps our unit dry and condensation free, even on the Oregon Coast. Currently 99% humility outside, and 40% inside.
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Old 10-08-2018, 09:25 PM   #8
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And while you are at it don't forget to visit your local Dollar Tree! I have no less than 10 of these hidden throughout the fiver...and yes they work!!!
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Old 10-09-2018, 04:28 AM   #9
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Quote:
Originally Posted by BamaRam View Post
Thanks to all for the ideas. I understand the concept of opening the vent. However the DW will have no part of it. Loose to much heat, she says.

During the summer (because it was very hot) I removed the vent in the bathroom over the tub and found the framing for the vent was not insulated or sealed. I used foam board and caulk to seal it all up. It sweats in this weather but not to the point of dripping. Maybe the front needs the same treatment.

The vent pillow looks interesting. Do they get moisture on them?
Ours doesn't. If it sets in tight the insulation against the exterior surface is greater than that in the walls/door. The pillow will solve your dripping issue but not your moisture issue. You will have mold if you don't remove the moisture one way or another.
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Old 10-09-2018, 06:36 AM   #10
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Originally Posted by Alpine View Post
And while you are at it don't forget to visit your local Dollar Tree! I have no less than 10 of these hidden throughout the fiver...and yes they work!!!
I hate crystal humidity absobers! If the liquid in them spills you will never get that surface dry again!!!
Invest in an electric dehumidifier and enjoy, zero condensation!
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Old 10-09-2018, 08:22 AM   #11
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As most of us realize or find out, the RV is not a stick build home. Moisture and
condensation will ruin the RV and happen in ever one in many places here in the US. The vents, they are there to help and the easiest/cheapest way to prevent that problem. Just crack them open, turn the furnace on higher if your cold. If not, then you need to purchase something to take all that moisture you make out of air. We had a park trailer, and 28ft TT and later a home on the coast. All the products mentioned worked for us in that wet climate. Bottom line those vents do work and work better with a window also cracked open.
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Old 10-09-2018, 09:08 AM   #12
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If you have a ceiling fan run it on low or a small portable fan on low with the vent & window slightly cracked open.
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Old 10-14-2018, 07:44 AM   #13
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If you are hooked up to power the only way to go is using a "big" dehumidifier. All your humidity problems will be gone and you won't have to crack any windows.
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Old 10-14-2018, 08:17 AM   #14
flybouy
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Quote:
Originally Posted by BamaRam View Post
Camping in low 40s temperatures. The front roof vent is sweating onto the bed, leaving a wet spot.

I checked around an the only other condensation I can find is on the door and windows frames.

Thinking of using foam sheathing cut to fit the vent hole to block warm air from collecting in the vent cavity.

Will this work?
Also remember this when storing: You should keep a vent cracked when storing the camper. It's essentially a tightly sealed box like a large refrigerator. A S&B house has a much larger volume of air. Typically you door at home gets opened several times a day. The attic is ventilated and windows, doors, outlets, etc. leak air from outside. The camper is just the oposite.
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Old 10-14-2018, 10:19 AM   #15
pitman44
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We had a similar problem when cool weather camper, but ours was more extreme. Windows and walls with droplets on them. We took a vent near the shower, actually a skylight in our case, out and replaced it with a Fantastic Fan. Run the fan when we shower and haven't had a moisture problem since. And we've done a bit of sub-20F camping without a problem.
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Old 10-14-2018, 01:00 PM   #16
bill-e
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I would also recommend cracking the vent. My bedroom vent is open all year round. I also use a dehumidifier when parked. This inexpensive unit (Pelitier type) is quiet and removes enough water to make my RV dry. It even worked well when I had a Hybrid with tent ends.

Eva-Dry Humidifier
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Old 10-15-2018, 04:08 AM   #17
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Quote:
Originally Posted by jsmith948 View Post
Best way to prevent a build up of condensation is to crack the vent open to allow the warm, moist air to escape.
That is what we do too.
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Old 10-15-2018, 04:33 AM   #18
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nope

Quote:
Originally Posted by rhagfo View Post
Just get a dehumidifier a 30 pint unit keeps our unit dry and condensation free, even on the Oregon Coast. Currently 99% humility outside, and 40% inside.
Opening the window will let in more of what your trying to eliminate. This idea works. Walmart $150.00. I ran a permanent drain hose with quick disconnect to the underside of the camper.
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Old 10-15-2018, 06:48 AM   #19
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Quote:
Originally Posted by BamaRam View Post
Thanks to all for the ideas. I understand the concept of opening the vent. However the DW will have no part of it. Loose to much heat, she says.
All the more reason to snuggle up
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Old 10-27-2018, 08:03 AM   #20
shermris
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Dehumidifiers work well in travel trailers, the room-temperature humid air enters the dehumidifier, where it’s then cooled to its dew point, which results in its releasing its moisture, which goes into the water tank. The dried air is then heated by the combination of latent heat of condensation, which is a natural result of the process, and by circulating through the condenser where heat is exchanged from it to the air. There’s also some additional heat generated by the dehumidifier’s air compressor. The overall result is that the air going back into the room might be warmer than it was going in, usually around 10 to 15 degrees so you will gain some heat. The downside is that if your paying for electricity they cost about the same to run as a full size refrigerator. Opening vents works fairly well if the vent has an exhaust fan, they do expel warm air but if your using a trailer or motor home in cold weather your likely going to have to do something to deal with humid air. I like to use an electric heater if I don't need a lot of heat but the air exchange you get from running a furnace is not there so moisture build up is more of a problem. If your moisture problem is not too severe there are small low cost dehumidifiers designed for smaller rooms or spaces that are economical to run.
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