Hello! Newbie here. I know this must be a frequent question but I did search the archives and FAQ and didn't see a direct answer. My apologies if I missed something. I just purchased a Jotul 3CB. I have a prefab "out and up" style chimney according to some things I read here. This is a zero clearance setup with a 8 inch stainless steel inner pipe inside a larger 10 or 12 inch pipe. It is a 2 story chimney and goes straight up. I am aware of numerous clearance topics, etc but have a question specifically about whether I need an additional 6 inch stainless steel flex liner installed. The fireplace store owner's son was adamant I needed it - he seemed to live strictly by the manufacturers instructions. Hard to fault him there. The owner said he was walking on thin ice discussing it but felt I would be fine using a reducer to convert the 6 inch stovepipe to fit the 8 inch pipe at my damper. My neighbor has used the simpler method (reducer stright to 8 inch pipe) for his woodstove and said I should do the same. I appreciate your opinions. My thanks to the webmaster for making this forum possible!