Just wanted to share - finished the install on the new Drolet Columbia II and insulated liner. Got the liner from Rockford. The only trouble was making the turn from the shelf into the appliance connector, - the liner was not flexible enough even with the extra room from cutting out the damper frame beforehand . Had to use a black pipe from the stove to the connector. Chimney is 15', interior 13"x13" w/clay liner. The existing tile "looked ok", but why take the chance. Block-off plate is next.