Trailer Vented With Furnace On?

GordonThree wrote:
Arguing until the cows come home is a favorite pastime for many on this forum. It's how a question that should take one page to answer grows into a thread 3+ pages long :)

Actually, the cows some home every night and put themselves in the barn. People on the forum can argue for days.

It may seem wrong to let heated air out, but you MUST get the moisture out. An electric dehumidifier is a good idea if you're going to use it much in cold/wet weather and without one, cracking a couple of windows and vents open is needed.

If the humidity level is allowed to get too high inside, moisture will migrate to the underside of the roof and through the walls to the outer skin (where it is cold) and condense into water. Over time it can cause serious damage. RVs are built wrong in terms of wall and ceiling/roof assemblies because the impervious layer/vapor barrier is on the outside and not the inside like in a house. They use open-cell and batt insulation and when that gets moisture in it, the R-value goes down making things even worse.

We have a Maxxair fan in the bedroom and bathroom. Regardless of outside temp., we always have a window in the bedroom and rear of the TT cracked open and run the bath. fan on 10 or 20 percent speed at night. Running the fan in the bedroom doesn't do much because the window is too close to the fan and it short circuits.

Another reason to get some air exchange happening is because of CO2 buildup. If you wake up in the morning with a headache and/or feel stuffy that's why, esp. if you have a separate bedroom with door. With cool fresh air coming in during the night in our TT, I sleep way better compared to home.

Having a hygrometer is a good idea so you'll know exactly what the RH level is instead of guessing. I'm always amazed by how much water collects in the 2 dessicant dryers we have over the winter and that's with nobody using the TT. Over the first winter after we got our new TT, many of the wood trims around the inside and exterior doors went snaky from the moisture and had to be replaced. That's when we got the dessicant dryers. Joints can open up on some cabinet doors too.

One option might be an Eva-dry "petite dumidifier". No noise and shuts off when the tray is full. Available on Amazon for $50. You might need several of them depending on your floor area.

Spent several winters in different rv's. Never had a window open when it's cold enough to run the furnace. I would sometimes keep the bathroom vent open unless it was really down in the low teens or close to zero.

As mentioned, rv furnaces are vented to the outside so we never built moisture or humidity from the furnace. The gas stove on the other hand has always been a source of moisture when cooking. We always vent more or crack a window open when cooking on the stove.

Wife is always right. Do the venting! And ... it's OK to do a little "venting" on RV.net too!

Arguing until the cows come home is a favorite pastime for many on this forum. It's how a question that should take one page to answer grows into a thread 3+ pages long :)

People can argue until the cows come home about where the moisture comes from.
Does it really make any difference? No. The fact is that when it is cold outside and warm inside, you will get moisture problems if you don't ventilate or use a dehumidifier. And moisture is an enemy of your trailer.

You breathe, you sweat, you cook, you take a shower. That puts moisture into your camper. Warm, moist air comes into contact with cold surfaces - trailer walls and windows. Condensation happens.

This isn't rocket science folks. Anyone who has been in a camper in cold conditions has experienced this. A vented furnace isn't directly contributing moisture to the air from burning propane because that moisture is exhausted to the outside. BUT it is still contributing to the problem because it is warming the air in the camper, which is part of what causes the condensation problem.

mike-s wrote:
Which furnace do you have? One of the common propane ones with intake/exhaust vents on the outside? They don't add moisture to the inside air.

Ditto.

It's not the furnace that's causing condensation (on the windows I presume) Condensation is forming on the windows due to the cold outside temp and the small amount of moisture in the air from breathing, or running the propane stove for cooking. The colder it is outside, the worse the problem is.

Some venting is a good thing. I usually crack open the bathroom vent a little bit

Funny thing is, I'm the one who always had the vents open in the old trailer year round. We had a vent above our bed & on cold nights I'd leave just that one open for our breath to get out. Our new trailer has no bedroom vent so I guess I'll continue leaving the others open.

I have not wintered in a camper... but, I can't imagine not venting a (relatively) small box like that. I would think venting (at least a little bit) would reduce condensation. Plus, you would get fresh air in and stale air out.