Re: Where does the fresh air exit?
I found some answers.
The air venting system exhausts air through the bottom rear on each side of the van. You will find a couple of slotted covers on the bottom rear pillars. This opens to a cavity behind the plastic bumper. The outside outside opening has soft rubber flaps that prevent air from coming in, while allowing air out. SO TO VENT THE LOWER PART OF THE VAN, WHERE CARBON MONOXIDE AND PROPANE WILL ACCUMULATE, YOU MUST HAVE POSITIVE PRESSURE IN THE VAN.
If you run the vehicle Vent/Heater/AC system brings in fresh air creating positive pressure that exits through the bottom rear of the van. I think this is important because carbon monoxide and propane are heavier than air.
Likewise, when you are parked and run the roof vent fan (Fantastic Fan, etc.) set to IN with windows closed, air will circulate through the van and exit low. Again, this should flush out the heavier propane and carbon monoxide. This would work on those cold nights that you use an unvented propane heater. If your battery runs down and the fan quits, you have lost pressure and the system fails. Carbon monoxide and propane could accumulate in the van.
Also, if you run the roof vent fan (Fantastic Fan, etc.) on OUT, no air will come in through the floor exhaust vents in the rear of the van. You must open a window --> or if you have the vents on TOP of the dash open air will come in there.
Then, with the roof vent, you have the issue of rain...
This is a little tricky, and there seems to be some risk of doing things wrong.
I am considering putting a passive vent (read opening) low in the van, perhaps using the the plastic box under the passenger seat, maybe with a 12 volt computer fan to pull the colder air out.
Any comments or information will be appreciated.