I put a bedroom AC in our 20-06 Big Horn 3600 and it was not vented, but worked very well. We also put a small fan in the bedroom to blow the cool air down the steps into lounge area. In July, 2014 we took deliver of a big Horn 3875FB and had the factory install the bedroom AC. It is vented and works great for cooling the front area as well as the kitchen and lounge area. When we toured the factory during the Heartland rally in June, 2013, I was told the front air would not be vented if installed after the unit was completed and shipped to the dealer. The venting of the front air must be down during construction. Happy camping and safe travels to you.