For context; I’m full time in a 2016 transit with plastic bottle insulation behind thin plywood (roof and walls). Its just me in the van, I cook once a day and make a coffee in the morning…both using propane/butane mix.
Ventilation is via windows open sufficiently to match the surface area of the max fan located over platform bed at rear of van.
Heat is dry from a planar 4kw diesal heater towards front of van that I’ve run ducting from to distribute heat into living area between boarded front of bed and cab/living area bulkhead (door cut in so air can flow), under bed and blowing on me on top of bed.
I think I understand the principles of condensation and that I need adequate and effective ventilation to manage it while adding dry heat to stay comfortable/override the associated cold that ventilation brings with it.
I have been running my fan on 20% exhaust speed for the last few weeks and while I’ve been able to mostly avoid internal condensation (inc all glass), I have noticed persistent condensation on the metal rood behind the ceiling insulation (I can get my hand behind an unfinished section and took a few panels down to investigate last week). We have been between -3 and +9 deg Celsius for the duration of my time living in the van.
My guess this is due to either insufficient or ineffective ventilation.
One theory I have is that the fan speed is inadequate to remove the volume of moisture I’m producing.
The other theory I have is that it’s due to ineffective air flow between insulation and ceiling boarding.
I’m leaning to the later as the un insulted metal over the cab is staying dry but thought I’d see what others do fan speed wise in winter incase I’ve running it to slow?
Long post so thanks for reading if you did.