Question: I am trying (thinking) of converting my wood burning fireplace into one with a woodburning insert. The whole where the damper is is only 4.75 inches wide. Do they make pipe that fits through there and flexes a bit? Do I need to run the pi[e to the top of my 16 foot chimney? Answer: Yes, the flex pipe that runs from stoves or inserts is oval on one end to allow for this. In most cases, running the flex tube up 4 or five feet is OK, however a lining to the top is definitely a good idea if it fits into your budget. If your chimney is sound and drafts well, the short tube should also work fine.