Chebanse: a liner for a wood insert that was installed without one
A “slammer” install is an insert pushed into a fireplace with no liner. They were common for decades. Here is why they build creosote where nobody looks.
What a slammer is
A wood-burning insert is a stove designed to sit inside a masonry fireplace. It is supposed to connect to a full-height stainless liner running from the insert outlet to the top of the chimney. For years, though, installers simply pushed the insert into the firebox, sealed the front with a metal surround, and let the exhaust find its own way up the old fireplace flue. The exhaust leaves the insert outlet, hits the smoke shelf and the huge cold smoke chamber, slows down, cools, and drops its creosote there, behind the insert where no one can see it.
What we found in Chebanse
A 1950s house near American Legion Park with an insert that had been in place since the late 1980s. The homeowner swept the visible flue with a brush from the roof every couple of years and thought that covered it. When we pulled the insert, the smoke shelf and smoke chamber held a layer of creosote several inches deep in the corners, mostly the crunchy stage two variety with glaze underneath. The flue tiles above were cracked in two places, likely from a small chimney fire the family never noticed. Draft had been poor for years; the insert smoked when the door opened.
The fix
We cleaned the smoke chamber by hand, then installed an insulated six-inch stainless liner from the insert collar to a new top plate and cap. The insert went back in level with a proper connector and a block-off plate closing the damper opening. The homeowner burned the first fire that evening and called to say the door no longer smoked. Every insert we see without a liner gets the same recommendation, and NFPA 211 and every insert manufacturer agree.
If this sounds like your house: we handle chimney relining for inserts across Kankakee County, and our Chebanse page covers what we usually find there. Call (815) 449-4264, 7am to 9pm, any day.
Quick questions
How do I know if my insert has a liner?
Look above the insert with a flashlight. If you see the old fireplace damper and smoke chamber rather than a metal pipe, it is a slammer.
Is a slammer install illegal?
It does not meet NFPA 211 or the manufacturer instructions, and most insurers will not cover a fire that starts in one.
Does the insert have to come out to install a liner?
Usually yes. We pull it, install the liner, and reset it level.
Will a liner fix the smoking when I open the door?
Almost always, because the insert finally has a flue sized for it.
Published October 2, 2026 · By Jacob Dove, Friendship Chimney Sweep, Bourbonnais IL