Wasn’t sure where to place these questions for discussion. Moderators feel free to move if need be. This thread is about gathering information about these liners. Anyone have any experience with these round clay liners? Pictures of an existing chimney with these liners? Clay Chimney Liner, Clay Flue Liner, Round Flue Liner, Square Flue Liner Wall Thimble / Clay Thimble for Appliance and Stove Connection Also, is their any data available on how flue draft is affected in square liners, if draft is affected at all? Round versus square? I can see these tongue-n-groove liners being useful for straight liner alignment up a chimney flue. Especially for someone wanting to build a new masonry chimney or even to re-line an existing chimney. Seems the joints could be better sealed as well without the seal coming out. Joints could still expand but not move and shift around side-to-side.