I have a new 3500RL with the Washer setup over the storage, I think I will go down the floor and out the side in the white part of the trailer by the Battery somewhere. In my old unit I went through the wall because I had no room for the 4" pipe behind the washer. I love my Splidide 2100 vented outside. As long as the pipe runs downward to drain the water out. The spledide hardly let real moist air out maybe I could vent it in the battery open to the bottom area, that way no vent in the side wall