Chimney liners and code ?

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.

Slimdusty

New Member
Aug 22, 2023
56
Washington State
A question for the experts here. A masonry chimney, oftentimes get a SS liner installed for a new stove/insert install. This liner, to meet code must be insulated, correct? Why is this the case, whereas previous to the liner install one would use the fireplace and have direct flame/smoke exhaust on the clay chimney tiles without safety issue, assuming the chimney is in good shape. It seems like a SS liner, insulated or not is one extra layer of protection? What am I missing? Thanks!
 
The stainless liner provide a continuous exhaust path that is properly sized to the stove but not heat protection. If the liner is up against the liner or bricks in the chimney that heat will be transmitted through them. If there is wood in contact with the chimney then it may be subject to pyrolysis. An insulation blanket ensures a safe, zero clearance margin and is required unless the chimney has 2" clearance for an interior location and 1" clearance for an exterior chimney.
 
Thank you begreen. So, an uninsulated stainless liner would transfer more heat into the masonry chimney versus burning in an open fireplace exhausting straight into the masonry flu?
 
Thank you begreen. So, an uninsulated stainless liner would transfer more heat into the masonry chimney versus burning in an open fireplace exhausting straight into the masonry flu?
No. The current clay lined chimney doesn't meet code and poses a safety issue as is
 
Adding a liner means the chimney needs to be brought up to code compliance. The code issue was just explained in this thread.
 
  • Like
Reactions: Slimdusty
Thanks, that thread cleared up my confusion on the subject. Basically like most other renovation projects, once you alter or do any work you are required to bring the space up to code. An old chimney is essentially “grandfathered”in until a new install happens