Photomike,
For our always carpeted RV's? Years ago we bought 3 Dirt Devil hand vacs and one small collapsable Dirt Devil upright for the MH's, TT's & 5th wheel trailers when they had the aluminum vanes. They are plastic vanes now and if you pickup any thing hard like a small piece of gravel, the plastic vane shatters. Had it happen on our sailboat carpet the first time we used the new one we bought for it and had a struggle getting Dirt Devil to replace the hand vac. The replacement still sits in my pole building on a shelf since.
Our Son found a couple of the old aluminum vaned Dirt Devils, one in a garage sale and one in an estate sale. They are perfect for use in and RV as they have the rotating beater brush hitting the floor and carpet which bounces/bats the dirt so it's sucked in. Works great on our Siberian Husky's hair also. We use the Dirt Devil paper filter bags inside the cloth bag and it works fine and no dust blows out ever.
Yes, 50% of heat is lost thru the noggin (roof/head), 25% thru the walls, and 25% thru the floor. Best bang for the buck is the roof or top and next is the floor because it's so much smaller in area than the 4 vertical walls. Did I say we love thick plus carpet yet??? ha ha