I have built a barrel type oven that is 33" x 34" inside cooking surface. Barrel shape is 16" high. I will step down to opening height of 10" x 18". Will a 6 round flue be adequate? I was told that I may need 8", but it seems too big to me and seems it will let too much heat out. Of course I don't want smoke backing up either.
6" is fine but must be square not round