Bought my 45 year old house a few years ago. Had chimney cleaned this year. I have had 2 successful fires and 3 smoky disasters, downdraft? I notice inside the stove at the flue there are pieces of what look like patio block. The chimney sweep said they are shaped like a puzzle, and he had trouble putting them back after the cleaning. I don't know if there is a damper, I would have to remove the big trim piece above the stove (too cold). I wonder if these "patio blocks" are meant to be removed during heating season. Appreciate your help!
![[Hearth.com] what is this? [Hearth.com] what is this?](https://www.hearth.com/talk/data/attachments/291/291670-eff76913546136dca0ab036e1354b58a.jpg?hash=ey-oMGkTOm)
![[Hearth.com] what is this? [Hearth.com] what is this?](https://www.hearth.com/talk/data/attachments/291/291672-7c754b7bff27d7804a9f8f28ddfaefed.jpg?hash=YoOYYBet-_)
![[Hearth.com] what is this? [Hearth.com] what is this?](https://www.hearth.com/talk/data/attachments/291/291674-c58c1d117640809584a4d805b2445bd7.jpg?hash=OAasIA_ebq)