One of the cookstoves I am looking at calls for 7" pipe. I can get 6" or 8" Class A in stock but 7" is a special order, more $. The class A will go up about 15' to be above the peak of my roof. I am going to build a chase around the pipe. With that height I would think 6" would be large enough. I can install 8" but wonder if that will have to much draft.
Doug
Doug