Ventilation of under belly

[Jimmer]

I have a 2021 Reflection 315RLTS travel trailer. I was recently under the travel trailer cleaning/painting the frame of the travel trailer and noticed some moisture at a cut portion of the coroplast. Upon dropping a portion of the coroplast, I noticed moisture in the under belly. It had been 2 months since I drove to Florida and encountered a rain storm, so that moisture likely was in the under belly for 2 months. I left the under belly/coroplast open for a week (while I lived in it and was connected to a water hose), and the underbelly had completely dried out, no more moisture. Thus, I assume there was no leaking plumbing causing the moisture.

I taped up the cuts in the underbelly to reduce as much as possible moisture getting in there, but I accept that moisture is going to in there from water spray from the tires when driving in the rain. For example, there is an opening through the frame for the spare tire raise/lower shaft near the trailer wheels, so water can definitely get in there. (Last year, I had a 110 volt short in a removable connection in the underbelly area due to water in the connector.) Water was coming in where Lippert cut the under belly to bring out the wires for the automatic leveling system they installed, and hopefully I have that all sealed up now.

Accepting that moisture from road spray is going to find its way into the underbelly, it would be nice to have some type of openable/closable hatch (preferably with a fan) that can circulate air through the underbelly to dry it out when I'm parked. Has anyone every done anything like this? (install a vent and/or fan to air out the underbelly when parked?)

[Yoda]

The other source of water in the underbelly is condensation, It can cause drips too. As for ventilation there is furnace ducting in the belly, so possibly running the furnace fan might work, if that can even be done without using heat.
Keith

[Jkwilson]

You already have an opening to the underbelly with a ventilating fan. The furnace.

[howson]

Yoda and Jkwilson

To run the furnace without calling for heat (and wasting propane), Jimmer would have to figure out a way to alternatively power the blower. I'm sure he's more than capable of figuring this out (the schematic is easy to read), but even if this was done the majority of the air from the furnace will be recycled inside the trailer. It will certainly work, but not the most efficient IMO.

The first thing that came to my mind was Cate&Rob 's "bomber door" modification. There's a link to Rob's mod in this post: https://gdrvowners.com/forum/operati...6608#post16608

The premise, though, that water intrusion of that magnitude is acceptable and normal is (in my mind) questionable. Between Gorilla tape on the edges and expanding foam the wide gaps around the plumbing and propane lines that enter through the coroplast can and should be filled. The largest (unfilled) areas on my 315RLTS are where the slide manual extension/retraction rods go through the frame. Even those could be (mostly) sealed with gorilla tape.

[Country Campers]

Another good place to introduce water into the underbelly is when filling the fresh tank with cool or cold water on a high humidity day, condensation would ensue on the outside of the fresh tank. I agree that road spray when traveling in the rain would be the worst culprit but any water in there could cause issues. I have never thought about this before and I do fill my fresh tank from my well which would cause condensation.

Brian

[Cate&Rob]

Hi Jimmer,

I wouldn’t worry too much about this. Trailers like our Reflections without batt insulation sitting directly on the coroplast can tolerate a small amount of moisture on the coroplast without any concern. I have a moisture alarm cable laying on the upper surface of the coroplast under the tank drain valves and it will go off after towing in the rain or even temperature changes that create condensation. A few days later the sensor cable is dry. As noted in post 4 it is easy for me to open up the underbelly to check (which I have done). This might not be true for larger rigs like Solitude with batt “sponges” laying on the coroplast . . .

Rob

[Jimmer]

Great comments, folks! Love the bomb bay door mod! That's very cool and would provide good ventilation without a fan.

I guess the real question is how much moisture is acceptable and is an underbelly vent worth the time? The reason I'm thinking about this is that my floor is starting to make creaking when I walk on it at the back half of the RV. There were no opening/holes/wheel spray from the trailer in the front of the trailer, and the floor doesn't creak when walking on it in the front. The trailer is exactly 2 years old now, and I live in it about 4 months per year. Maybe the flooring material is aging, but maybe this creaking developed because of the moisture in the under-belly.

I had openings into the underbelly from where Lippert cut the coroplast to bring out the wires for the rear leveling jacks, and those openings were definitely a source of water intrusion and are completely sealed now. I guess what I'm going to do is tape up the frame holes for the spare tire lift (and the rear slides, if applicable) and see how wet it gets in the underbelly after the next drive through the rain. If the moisture is non-existent, then the problem is solved simply by sealing the coroplast better. But if there is moisture in there after a very thorough sealing, I will further investigate the vent fan concept.

It's good that there is no insulation to get wet in the underbelly. If this were a Solitude with the bat insulation, the project would have much more urgency.

Thanks again for your ideas!