MAXXFAN Deluxe features the INDUSTRY EXCLUSIVE built-in rain shield eliminating the need for any additional covers.
For a B van, if you want to keep the low profile look, a Maxxfan Deluxe model is a nice option. Maxxair - High Powered Ceiling Fans for RVs | Airxcel
It's a fair bit of $$$$ though to replace a good and working Fantastic fan with a Maxxfan Deluxe though.
I have one Maxxfan Deluxe on my trailer and one Camco Aero-flo RV Roof Vent Cover. Aero-flo RV Roof Vent Cover - Camco (the trailer has two 14" sq vent holes)
I don't yet have a fan under the Camco but plan to add one if needed.
I don't think you can get a much less expensive cover than the basic Camco's. The Aero Flo costs a bit more but they say it has "30% more open vent area". It still costs way less than the Fantastic cover. I figured it was a low cost way to still get OK performance if I end up adding a second fan.
Camping World has the Ultra Breeze on a sale price for $38...
I've been looking at the Ultra Breeze cover as well.
Camping World has the Ultra Breeze on a sale price for $38...
This Fan-tastic video is very convincing.
Yeah, it convinces me that when the time comes I'm going to install an automatic opening/closing vent with a rain sensor on my roof because there is no way in hell I'm putting something that ugly up there.
Fantastic makes upgrades from their most basic unit to their most feature -rich version for less money than a complete fan and you never need to remake the seal on the van roof, just upgrade the guts. I'll go that route.