Q: We just bought a wood-burner, and the guy at the fireplace shop says they aren't allowed to install it unless they
also put in a stainless steel liner kit all the way to the top of my chimney. Why would that be? What's in a liner kit
anyway? And why stainless steel?
 A: There are four situations relating to your existing chimney that would cause your code authority to require a
stainless liner for a wood stove installation:
1) The existing chimney is unlined. In the past, some masonry chimneys were built without any liner at all. Without a
liner, wood exhaust can leak through the mortar joints into the house. Further, liquid creosote will eventually dissolve
the binder in the mortar and soak into the joints, until the chimney itself could catch fire!
2) The existing chimney is lined, but the liner is cracked or damaged. Masonry chimney liners are made of terra cotta
clay or pumice, which can crack from chimney fires, settling, or other causes. Cracks in a pumice or clay flue liner will
let the smoke and liquid creosote through, leading to the same problems described above.
3) The existing chimney is lined, but the liner is too large. Oversized flues cause numerous problems, like smoke
spillage into the house when they're cold, stove overfiring when they finally heat up, and the kind of excessive creosote
formation that leads to chimney fires. Code prohibits venting any woodburner into a chimney flue with a cross-sectional
area (CSA) that is more than three times the CSA of the flue collar on the stove. Thus, if your stove has a 6" flue collar
(28 sq.in. CSA), the chimney flue must have a CSA less than 84" (3 x 28). In other words, if the chimney flue is larger
than 10" round (78 sq.in. CSA) or 9" x 9" (81 sq.in. CSA), you must install a 6" stainless liner. This rule gets tougher if
one or more of the chimney surfaces is on an outside wall, so it is exposed to outdoor temperatures for its entire length:
in those cases, the CSA of the flue can't be larger than two times the CSA of the flue collar, so you must reline if the
existing flue is larger than 8" round or 7" x 7".
4) The existing chimney is air-cooled, like the manufactured metal chimney used for zero-clearance wood fireplaces.
Cooling the exhaust from an airtight woodstove leads to balky updraft, smoke spillage and excessive creosote
formation. Installing an insulated liner helps eliminate those problems.
Woodstove liners must be made of stainless steel, because up inside the chimney, wood creosote would rapidly turn
most other metals into swiss cheese.
Here are three typical "reline jobs", with a description of the parts required
|
Wood Stove Reline:
* Stainless Rain Cap
* Stainless Sealer Plate
* Stainless Flex Liner
* Stainless Flex Adapter
* Stainless Tee with Cap
| Wood Fireplace Insert Reline:
* Stainless Rain Cap
* Stainless Sealer Plate
* Stainless Flex Liner
* Stainless Flue Collar Adapter
For reliner kit pricing, click here.
| Wood Hearth Stove Reline:
* Stainless Rain Cap
* Stainless Sealer Plate
* Stainless Flex Liner
* Stainless Flex Adapter
* Stainless Tee with Cap
|
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