My 2015 Winnebago only had a couple holes in the floor under the head of the bed with two grilles in the bed base. I ended up adding a 3" computer fan to one of the holes to make sure enough warm air found it's way down there after having some minor freezing issues in the utility bay at 20 degrees. I just wired it to the coach's 12 volts. It uses such a tiny amount of power the I have not experienced any battery drain issues (it gets powered down when I turn off the coach batteries). I really thought there would have been a duct, but not my Winnebago.