Anyone setup ventilation through existing cabin ducts?

[Furi]

I wanted to add proper ventilation/airflow to the cabin as part of a camper built but try not to change the aesthetics of the van as much as possible; i.e. replacing moonroof or window with a vent, etc.

Was wondering if anyone has tried to use the existing back AC ducts/channels to do this? I don't need the AC in the back and was thinking to remove it creating some space and putting in an efficient fan or blower, running off house battery, that would be connected to the existing channels and vent outside; or reverse and bring fresh air in. Anyone tried? Thoughts?

[ChuckBlack]

Ive seen something of the site where the heating system had been removed from the back to be replaced by a water heater... Warm showers are always welcome camping. But i'm sure with patience and some knowledge you'll figure it out! Good luck!

[Growlerbearnz]

I considered it when I was camping in my van. On hot nights it was really nice to have airflow, but I identified a couple of issue: 1) the rear fan uses a lot of power when on low speed and 2) it only recirculates air from inside the cabin.

For 1) I had planned to drive the fan with a pulse-width modulation controller (rather than the standard setup, which burns power in a large resistor to get low speed). That should get the gentle airflow you're after while using much less power.

Issue 2) is a little trickier. I thought about adding a vent to the outside of the van, intersecting the intake duct, so the fan would draw fresh air from outside as well as from inside. Not sure how good it would be while driving though, perhaps some kind of vent that could be closed?

[Furi]

Growlerbearnz...
Did you mean using the existing fan/blower? I was thinking to take the whole unit out and install a more efficient fan in the wall with a voltage controller and pipe it outside under the car; with option of closing it off. That way I could exhaust as well as bring fresh air in. But I'm not sure if a fan that is efficient enough in that setup would be effective; i.e. pull the air through roof ducts down the side walls and push it outside, and vise versa. Was hoping someone tried it..

I will check out the pulse-width modulation controller; thanks a bunch.

ChuckBlack... I believe Felix@Dinoevo did the modification of replacing the unit with a diesel water heater. Pretty awesome setup. Hot water on tap is on my list but having to do with the coleman black bags til I get enough time and money to upgrade to proper plumbing :)

[Growlerbearnz]

My plan was to use the original fan, yes, but I hadn't considered using the system to extract air. It's quite a clever idea!

The existing fan is a squirrel-cage fan, so it will only push air in one direction even if you run the motor backwards.

I wonder if a 6" 12V computer fan would work? You still can't drive it backwards (the motors don't like to be connected backwards) but you could install two of them facing in opposite directions, and turn on whichever one you wanted... You wouldn't get much airflow, but you don't need much for extracting humid air, or creating a gentle breeze while sleeping. I have a 6" computer fan set up as an extractor in the bathroom of my caravan, and it's quite adequate to remove steam when showering. Surprisingly, it hasn't failed yet, despite the amount of humidity it has to deal with!

I'm sure you've looked by now, but PWM DC motor controllers are about $5-$10 on Ebay. The only potential issue is that the inexpensive ones modulate the negative rail, so you have to make sure your fan motor isn't also earthed through the motor body. I don't think it's an issue, since the housing is plastic, but it's something to look out for.

[Furi]

Thanks again for the hints; stuff that could prevent a few days of banging your head against the wall wondering whats wrong :) Your fan in the shower is a good example. There are some descent computer fans in the market specially designed for tight spaces which might be useful in this case. I first have to take out the AC unit from under the car to create some space and save some weight. I'll give it a shot and see how it goes...

[Growlerbearnz]

I've left my AC in place, because it's much quicker to cool down the entire interior while driving if the rear AC is on.

Then again, it gets kind of warm here. I've added extra vents to the front duct of the rear AC, so it blows cold air down the back of your neck- it's lovely. (Also moved the sunroof switch so you can reach it from the drivers seat more easily.)

Vents.jpg (47.08 KiB) Viewed 5887 times

[stugots1982]

Personally I am considering something more along the lines of the computer or even just a portable fan to move air. I figure I can always run temp venting to a cracked window and seal it with a towel or something. Not a permanent ficture but as the weather in BC gets cooler I don't need to worry about losing the heat either. Just my 2 cents.

Stugots

[Furi]

Personally I am considering something more along the lines of the computer or even just a portable fan to move air. I figure I can always run temp venting to a cracked window and seal it with a towel or something. Not a permanent ficture but as the weather in BC gets cooler I don't need to worry about losing the heat either. Just my 2 cents.

Stugots

I pretty much ended up with the same setup right now. Couple of USB charging fans on front windows with rainguards. But involves moving fan's around, taking up storage, etc. Was hoping to move the fans outside of the cabin and make it a switchable process. Its a project though!!!