We use ours set on exhaust, and IMO, it should be at the highest (warmest) point of the RV, which in our case would be the bedroom. That also puts it nearby, so if it gets too chilly in the bedroom, you don't have to walk to the back of the 5er to turn it off.
It does create some soft "white noise" - but I LIKE that :-)
While we're talking about Fantastic Fans - that's the one thing our 5er lacks (and I LOVE those fans!). Is it possible that the wiring is already in place, next to the bedroom vent?? When we bought our then-new Class C, it didn't have a FF, and Ed said we wanted one as part of the deal. They happily installed one - I have a suspicion that it wasn't a very difficult thing to do? It's not like I can see wires run to it.
