Any RV window (thermal pane or not) is somewhat subjected to condensation/ moisture build up during relatively cold weather occupancy if air circulation is interrupted. What you need is to initiate a condensation/ moisture control procedure.
Most common sources for the moisture build up in RV;
a) Using the shower. Probably the worst, even with the vent fan running.
b) An open flame on the cookstove top, even if you didn't cook anything. Cooking anything even adds more. The byproduct of combustion, besides heat, is...water vapor.
c) Human and pet breaths.
d) Just naturally occurring trapped humidity.
Water vapor originating from occupant breathing is the major contributor over the course of a night; some ventilation is always required. At colder temps the air can't hold the water vapor and it condenses on interior surfaces. Ideally, we should have some type of exterior air exchange vent near floor level, but since we don't, you're going to have to lose some heat and open an overhead vent.
In your case, slightly crank open the bathroom/ bedroom vent and if that doesn't help, you'll have to turn on that fan as well to the lowest setting.
Originally Posted by ROC-REQS
We got thermal pane windows on our 2015 Eagle Premier. They were one of my must have options, which resulted in us having to order one because no dealer in our area order trailers for their lot with thermal pane windows. Go figure in WNY
Are they worth the cost? That's totally a personal opinion & decision.
However, we still get moisture on the inside of the windows in the bedroom, so either some of our thermal-pane windows are defective or I had false expectations on their performance.
Last time out camping was our first time with our new trailer where it got cold over night. Temps dropped into the upper 30s. I had the thermostat set to 62 and the furnace ran periodically through the early morning. So there was ~25Deg temp difference between the inside & outside temps.
In the morning we had major moisture on the inside of 2 windows. The windows in the living area were fine - no moisture.
I contacted Jayco customer service about it to inquire if the 2 windows may be defective.
The Jayco rep responded indicating that you can still expect moisture on thermal-pane windows.
Personally I felt the response from the Jayco rep was more of a company line blow-off. His exact response was:
"... Condensation will happen if the there is enough of a temperature difference from inside the unit to the outside. You can open your roof vent approximately ½” to get some ventilation in the unit.
I don't think 25Deg difference was significant and his response I felt was explaining how a typical standard window would perform, not thermal-pane windows.
Anyway, it made me feel like why did I pay the $$ for these thermal-pane windows when Jayco is telling me I can't expect any better performance then standard windows with regard to inside moisture.
I'm just sharing our 1st experience with thermal-pane windows in cold weather. Sorry if it sounds like I'm venting.
Would I purchase them again - probably.
I still feel the thermal-pane windows provide better performance then the standard windows. They do seem to help with temperature control inside the trailer.
Hope sharing our experiences and feelings on thermal-pane windows is of some help to others.