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Old 11-15-2010, 11:44 PM   #1
Join Date: Nov 2010
Posts: 48
Where does the fresh air exit?

New Sprinter Sportsmobile owner.

The dash vent brings in fresh air unless set to recirculate. Where does the fresh air exit the vehicle?

I am interested because I am considering installing an exhaust vent low in the vehicle to clear carbon monoxide and propane (which are heavier than air).

BTW, if if run the roof fantastic fan on exhaust, it pulls fresh air in throught the dash vent even with the engine off. It also pulls in a lot of air around the microwave/convection oven that sits over the fridge. Am thinking that needs to be fixed.

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Old 11-17-2010, 05:48 PM   #2
Join Date: Nov 2010
Posts: 48
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.

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Old 11-18-2010, 09:13 AM   #3
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Join Date: Apr 2007
Location: Franktown, CO
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Re: Where does the fresh air exit?

Originally Posted by SkinnyRV
Then, with the roof vent, you have the issue of rain...
If by roof vent you mean fantastic fan, the fan will close automatically for rain, or you can set it manually to be open part or all the way. If it's intermittent sprinkles the fan will open periodically, get wet on the sensor and close again. Of course if it's really raining and you're counting on the fan you can easily get sealed up if you don't set it to manual.

Instead of going to all this trouble to use an "unvented propane heater", why not put a safer option in the Sprinter? Then all this stuff is backup and would need to fail in conjunction with the vented heater system failure to fill the van with CO, right?

Also, I imagine you'll have propane and CO meter/alarms too- fairly cheap insurance for something other than battery failure (and I believe my CO alarm chirps with the house battery voltage gets low ~8v or something).
and then
everything changed
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Old 11-19-2010, 05:39 AM   #4
Join Date: Nov 2010
Posts: 48
Re: Where does the fresh air exit?

Right now the big probelm is the Microwave/Convection oven above the fridge. I have the three way because I need to have propane fridge for long periods while vehicle is parked. There is a big air leak around the Microwave. It pulls air in from the vent space for the propane fridge. Microwave is sealed to the cabinet, but back end sticks into the fridge vent space. Microwave side vent is inside van. Microwave back vent is in fridge vent spce. They resealed the microwave yesterday but I did not test the airflow before I left. Must be leaking throught the microwave cabinet. Am going back today to see what can be done.

You are right - my best bet is the vented furnace with thermostat. I am spoiled by the one in my Itasca Navion (View). Have had that vehicle in -5 F. (My version of Fantastic fan does not automatically close when it rains. Would not want that to happen while I am sleeping. Maybe a cover.) Also, I don't have a good spot for the furnace. I do like radiant heat. Nothing like staning in front of a heat source after being out in the snow.
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