Insulation & Ventilation

bcman

Active member
Hello All,
I just got a 2003 140wb high-roof passenger van, and I'm getting ready to do a DIY camper conversion. I know I want a roof vent so I can cool things off easily in the evening, but on my passenger van none of the windows open (other than the two fronts), so I'm wondering: when the roof vent is pulling air out of the van, where can air enter the van to replace it? I was thinking about adding a couple small vents down low like the ones at the bottom of the page here, but then I noticed some vents in the rear side trim panels:

Does anyone know, do these connect to the outside? Or are they there just to equalize pressure between the interior and wall cavities (or something like that)? If they connect to outside air, I'll try to leave them unobstructed when I insulate my wall cavities. If not, I'll either block them off with the mass-loaded vinyl barrier I'm installing, or replace them with the flip vents from Sprinter World.
 

GaryJ

Here since 2006
There are vents under the rear bumper corner covers. They do have flappers on them that essentialy make them a one way valve, out only. The little rubber flappers can be removed after removing the rear bumper, but dusty roads will allow dust incursion. Don't block off the air to them with inside panelling because they're necessary for the flow through ventilation from the dash air/heat.

Gary
 

bcman

Active member
It looks like it's pretty dusty back there already!

I'm thinking I'll get the flip vents from Sprinter World and mount them in the location of the vents in my trim panel. Then I'll drill some holes in the bottom of the black plastic trim rings for the flip vents, and mount those in place of the trim panel vents. Then I'll always have one-way venting out, and can open the flip vents to pull air in when using the roof vent.
 

GaryJ

Here since 2006
There are some black rubber plugs in the bottom of the rocker panels that can be seen from underneath the van. One or more could be missing and letting the dust in.

I'm not following your description of how you'll draw air in through the flip vents. Where does it enter from outside?

Gary
 

bcman

Active member
Air enters through the flip vents, but only when they're open. When the dashboard fan is running, it will still push air out through the one-way ports in the bumper.
 

GaryJ

Here since 2006
Still not quite clear on your plan. If you retain the one way ports in the bumper how will the flip vents when opened be supplied with outside air? It can't be pulled through the one way ports in the bumper if they're still operating as "out only".

Gary
 

bcman

Active member
I drew a quick diagram:

I'll drill a few holes in the flip vent trim ring, so these will connect the flip vent air passage to the wall cavity. THen air can always flow into the trim ring and out the one-way ports in the bumper, and when the flip vent is open, air can flow into the flip vent and out through the trim ring.
 

GaryJ

Here since 2006
Now I've got it. I thought when you said "I'll mount them in the location of the vents in my trim panel" that you were going to put the flip vents in the trim panel, not the exterior sheet metal. The diagam made it clear, and looks like it should work as you've designed it. Good example of thinking outside of the box.

Now as another idea, could you leave all the venting as designed by MB for the flow-through ventilation path from the dash outlets, and put the flip vents in another location that might be preferable for function or aesthetics? An example might be if you had a spare tire carrier on the back door the flip vent(s) could be hidden behind the tire.

Gary
 

bcman

Active member
It's true, there's no reason I have to combine the flip vents with the factory ventilation. I want to have them somewhere near the rear, and down low. My MaxxFan is going in pretty far forward because I'm keeping the rear a/c ductwork (for now), and I'd like to get air flowing through the whole van. And if they're low, I might get some passive circulation on warm days with the roof vent open and fan off. I'll study the flip vents when I get them - maybe the rear doors will work as well.
 

mdhastings

New member
Please forgive me if this has already been covered, I could not find this particular Insulation Topic.

I have seen numerous videos of people putting various forms of insulation into the ribs, beams and crevices of their vans. Does this actually make any sense, or serve any useful purpose? The metal completely surrounds the insulation and can easily cold bridge around it. Unless the inner metal surface of these ribs and beams is insulated, it would seem that the insulation job in these areas would be ineffective.
 

bcman

Active member
I can't say how effective they'd be in this specific case, but I can give you the theory: Yes, the sheet metal conducts heat, and there's nothing that insulation can do to stop that. However, heat can transfer from the outside sheet metal to the inside ribs very quickly by convection. If you can stop the air from moving inside the ribs, you effectively halt convection heat transfer. Hard to say whether convection or conduction is more prevalent through the ribs, but it's pretty easy to string strips of thinsulate through the ribs, and it weighs practically nothing, so if you've got the time I'd recommend it.
 

d_bertko

Active member
Openable screened windows make camping ventilation easier. Much of our use does not require the Fantastic Fan to be running. With three t-sliders we can adjust the ventilation to where we are sitting. The fan simply provides enhanced airflow but passive sure is nice when conditions permit.
 

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