My chimney is about even with the peak, and not far from it. I think I could benefit form another 3 feet of height. Surely I could get some block, mortar, and flue pipe and go that route, but I was wondering if there was a type of steel pipe readily available that transits nicely from square clay flue (6.5x6). Especially in this current weather, I don't really want to be trying to get blocks up there.