Condendation on ceiling

Hi Folks - We're currently on a trip from AZ to Niagara Falls and back. Into our 6th week of the trip. 2016 Bighorn 5th wheeler 3270 RS. Currently in the Great State of Kentucky for a week or so. Question: We've been using both AC units periodically during the entire trip. Just yesterday and today, we've noticed condensation (or frost?) on the bedroom ceiling. I washed out the little round air filters in the vents but nothing else. The moisture on the ceiling is directly beneath the front AC unit. Is this an indicator of something plugged up in the AC unit itself? Maybe a "frosty" refrigerant line or ... ? What could be causing this now and never has before? Additionally, high humidity outside (77%), temp only 75-ish. Thank you to all responders. FYI, I'm not an AC guy by no means; time to call the serviceman??

John
 

danemayer

Moderator
Staff member
Perhaps just an air leak letting the humid air in.

Sounds silly, but before calling for service, make sure all your windows are closed fully.
 

sengli

Well-known member
We just got back from a small outing, and I noticed the same issue on our rig too. Honestly we rarely use AC normally. Seems as if I have seen similar threads on here about this issue. The ceilings get sold cold they are sweating. Thats one reason they changed the build of the ceilings in the heartland coaches about two model years ago. The 2017 and up now have built up roofs, made with wooden rafter, and batt insulation with insulated duct work...... not made of laminated foam and aluminum structure anymore on the big country, big horn and landmarks anyway.
 
We just got back from a small outing, and I noticed the same issue on our rig too. Honestly we rarely use AC normally. Seems as if I have seen similar threads on here about this issue. The ceilings get sold cold they are sweating. Thats one reason they changed the build of the ceilings in the heartland coaches about two model years ago. The 2017 and up now have built up roofs, made with wooden rafter, and batt insulation with insulated duct work...... not made of laminated foam and aluminum structure anymore on the big country, big horn and landmarks anyway.
I guess that makes sense. So apparently no "fix" except to buy a newer rig, and we ain't about to do that. So it's another one of those little problems we have to live with. I wonder if Mr. Biletti could comment, please? Thanks guys.

John
 

travelin2

Pennsylvania Chapter Leaders-retired
What Sengli says...we experience same in very humid locations like in SC along the shore. The cold air in the built in duct cools the hot ceiling causes sweating. Just like removing something cold from the fridge, it sweats. Once the humidity in the coach drops significantly the condensate does too.
If you’re from AZ you likely don’t encounter that phenomenon there. We’re from the NE and when we go to the SW all the wood shrinks LOL! Here’s a picture of our cabinet door panels...
f49baf70dd668a15dd8db3a9a4cfcc9d.jpg


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What Sengli says...we experience same in very humid locations like in SC along the shore. The cold air in the built in duct cools the hot ceiling causes sweating. Just like removing something cold from the fridge, it sweats. Once the humidity in the coach drops significantly the condensate does too.
If you’re from AZ you likely don’t encounter that phenomenon there. We’re from the NE and when we go to the SW all the wood shrinks LOL! Here’s a picture of our cabinet door panels...
f49baf70dd668a15dd8db3a9a4cfcc9d.jpg


Sent from my iPhone using Tapatalk

Well, that/s not good either! But I guess heat, cold, humidity, dryness explains it. Our trim shrunk like that too in places. Bummer! But thanks.
 

Gary521

Well-known member
There was a problem with the AC's built around that time with drainage in the ACs. Pull off the cover and see if there is excessive water on the support structure. If there is, there is a drawing that you can get that shows where to drill holes that allow better drainage from the support structure.
 
There was a problem with the AC's built around that time with drainage in the ACs. Pull off the cover and see if there is excessive water on the support structure. If there is, there is a drawing that you can get that shows where to drill holes that allow better drainage from the support structure.
Where my I obtain this drawing?
 

NHCelt

Well-known member
Where my I obtain this drawing?
There were several issues with the 2016 Dometics. I had them all, and experienced the condensation that you are having.
At some point I posted a whole series of posts with pics here...but the gist of it is;

There is a drawing from dometic that indicates the locations and sizes of additional holes to drill to allow excess water to flow to the outside of the ac. Part of what is happening is that the drip pan is overflowing into the ducts.

Secondly, I found that there were mounting holes that were left unplugged, and that these drained directly into the ductwork. Use a small light in the plenum shining up on the drip tray and if yours are not plugged you will see light coming through. I think it was toward the front just inside the roof gasket

Third, excess rainwater enters the ac unit through the cover where the top fits into the bottom. Mine had big gaps and the water would overwhelm the drip pan and go right into the ductwork. My fix was clear Gorilla tape around the entire seam.

Fourth, my duct run was open on both the front and the rear, and the ducts were not sealed at the plenum...you guessed it...cold and warm air mixing produces condensation. Block off the ends inside the ducts if they are open to the caps.

Take care of these and you should be good. Once I did this I never had another drop of water, and never had any more ceiling condensation.

But...my ac units both leaked under the gaskets. I took it back to the factory for that .

What a horror show it was, because these ac units were new and nobody knew what was going on.

On edit...I also used some stick on silver insulation inside the ductwork to line the ceiling as much as I could. I would do this only as a last resort...I think the other fixes will cure the issue. This insulation was one of my first attempts at figuring out what was going on. Might not be necessary...
Hope this helps you.



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MTPockets

Well-known member
This may seem counterintuitive, but condensation will occur with a lack of adequate ventilation. Open a ceiling vent or window to allow better air circulation.
 
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