Back In The Old Days…
Woodstove inserts were manufactured with the idea that you put it in the fireplace and you were good to burn.
Unlined Inserts
Inserts with no stainless steel liner installed to them have to be pulled out of the fireplace to properly clean the masonry chimney system. There is a large chamber above the fireplace damper that needs to be brushed from below (the “smoke chamber.” There is also a cavity behind the back wall of the fireplace that needs to be vacuumed out. This is the “smoke shelf.” Creosote and debris can fall into the smoke shelf during the chimney sweeping process.
And then there was fire.
The inserts had a 6″, 7″, or 8″ exhaust port that was venting up a masonry chimney flue that was much larger. This resulted in a mismatch, which resulted in the chimney flue not getting warm enough to prevent dangerous levels of creosote buid-up. Specifically, Third-Degree creosote built up in the masonry flue and the smoke chamber. This caused dramatic, damaging chimney fires.
The Code Is Written
Finally, the mechanical code was written that required stainless steel liners to be installled down the chimney and connected directly to the woodstove insert. These days we have light-weight, flexible liners that are extremely durable and relatively easy to install. The installation of liners cuts down on chimney fires dramatically because it is much easier to maintain the required temperature within the uniformly sized liner. that is properly sized for the stove (unlike a brick chimney flue, which is sized for an open fireplace.)
Flexible Stainless Steel Liner Kit
These liners are impregnated with titanium. They make the installation process much easier for the installer.
Back Wall Of Steel Firebox Cut Out For Liner Installation
The liner is installed down the chimney, and comes through the back wall of the fireplace to reach the back exhaust port of the woodstove insert.
Liner Connected
The liner has a ridged ‘T’ connected to the bottom so that attachment can be made to the exhaust port at the back of the stove.
Video: The author gets dirty cleaning an unlined insert!