Question: I have a pre-fab fireplace with a stainless steel chimney. It is my understanding that there is an outer pipe. Recently I had the chimney cleaned by a reputable chimney sweep. After he was finished I looked up into the chimney. I noticed the inner stainless steel chimney pipe was separated slightly from the fireplace. However- I do not know if the outer pipe shares the same malady. 1. Does it make a difference if the outer pipe remains intact? Or- should I have it inspected and repaired? Your advice will be greatly appreciated 2. Thank you very much for responding to my query. You mentioned that a chimney should not be oversized- and that lining it with a stainless steel pipe will help. Is it just the width - or is chimney height a problem as well? (Does it help to play around with extending the height?) Answer: 1.The inner pipe is the only one that carries the fire and heat..the other layer(s) are cooling pipes. The inner one should be smoke tight. One pipe fits inside the other (above into below)...if you really think it's separated- then have it checked out. 2. No- in your case extending the height 2 to 4 feet will not do anything except maybe give the smoke more time to condense. The width is the problem. If I'm not wrong- your stove uses a 5" pipe...you could use 5" or 6" pipe to reline.