Whatever works for ya. The foil ain't doing much though, heat rises. I have a closet in my house that has two furnace ducts running through it to the upstairs rooms and it gets very hot and dry in there. It makes a good hot box in the winter time of course my whole house gets down to around 30 percent moisture level in the winter time so the whole house is a pretty effective drying box in winter. In the summer I just run a wooden box with three 100 watt light bulbs in it.