I've got the Fiamma Turbovent 28 (the "crystal" see through version) on my camper, and overall I really like it.
For:
Easy to fit - you just need to cut a 28cm square hole in the roof.
Built in switch with reverse operation - blows air out or sucks air in.
Let's light into the van.
Opens wide for maximum venting.
Permanent venting so you can still get some venting effect even when it's closed and pissing down. I don't find it let's the cold in like you worry it might.
Built in mosi net to keep the bugs out.
Not noticing any wind noise when driving.
Spares parts are available if you need them.
Against:
Sit's quite high off the roof.
Fan is NOISY!
Fan is not variable speed - it's hurricane force or nothing. I'm going to fit a pulse width modulator to it, so I can turn the speed (and noise) down when I want.
Seems to let a lot of external noise into the van, even when closed.
It's worth pointing out that every other fan/vent that I looked at, were all permanently vented too.
I considered these but went with the Fiamma. I saw a couple fitted on vans at Transitmania - they looked really good.
http://www.ebay.co.uk/itm/Low-Profile-M ... SwnJVZoCXP
2011 SWB medium roof 2.2l Mk7 115 T300 in Frozen White. Stealth Camper converted.
"It's better to burn out, 'cause rust never sleeps..."