Thanks. That’s somewhat reassuring, I just wish I knew for certain what I have. Also wish I’d have known about this amazing group before I became a full time wood burner. I might have done something a little different before I bought a stove and had it installed. Not that I am having any problems, just didn’t do a lot of research beforehand. Oh well, live and learn. Learning lots here
Flex liner with insulation wrap/blanket in mason chimney. The house had a fireplace in the basement when we bought.IIRC it was pretty good looking pipe (heavy wall)