Ok, I'm missing something again... What am I protecting from the heat of the pipe? It's going to be inside a chimney that's designed to burn open fires. The chimney will be swept prior to installing. What am I missing?
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Ok, I'm missing something again... What am I protecting from the heat of the pipe? It's going to be inside a chimney that's designed to burn open fires. The chimney will be swept prior to installing. What am I missing?
Open fire burning is cooler in the chimney due to the large volume of air that mixes with the smoke. Wood stove flue temps can be much hotter. And usually a fireplace is not running 24/7.
Read up on pyrolysis. Long term contact of a hot chimney with wood drops it's combustion temp. We had a similarly constructed fireplace chimney that I removed in 2006. All looked ok on the surface. We assume it was original which would have dated it to around 1924. As I removed it I discovered that a lot of the mortar had turned to sand, that in several places wood was in direct contact with the chimney, that there were 2 take-off, one sealed with a plaster cap and one with wood over it!! The wood was charred. Point being is that old unlined chimneys are time bombs. They are often full of defects, can no longer have the required 2" spacing from any wood or combustible, and weren't made for 24/7 use. one can't predict when the wood ignition temp will be low enough for fire or at one temp.
Does this describe your chimney? I don't know, it would take an inspection by a qualified expert with a camera. And even then somethings can be missed. An insulated liner gives full peace of mind. FWIW, here is a picture of a 1977 chimney that was poorly constructed. This happened last year after 38 years of use. @bholler can quote you current code requirements for an unlined chimney if you need the documentation.
There is an additional benefit to insulating the liner. It keeps the flue gases hotter which improves draft and decreases creosote accumulation. This can be an important plus with a catalytic stove which often has cooler flue gases.
Read up on pyrolysis. Long term contact of a hot chimney with wood drops it's combustion temp. We had a similarly constructed fireplace chimney that I removed in 2006. All looked ok on the surface. We assume it was original which would have dated it to around 1924. As I removed it I discovered that a lot of the mortar had turned to sand, that in several places wood was in direct contact with the chimney, that there were 2 take-off, one sealed with a plaster cap and one with wood over it!! The wood was charred. Point being is that old unlined chimneys are time bombs. They are often full of defects, can no longer have the required 2" spacing from any wood or combustible, and weren't made for 24/7 use. one can't predict when the wood ignition temp will be low enough for fire or at one temp.
Does this describe your chimney? I don't know, it would take an inspection by a qualified expert with a camera. And even then somethings can be missed. An insulated liner gives full peace of mind. FWIW, here is a picture of a 1977 chimney that was poorly constructed. This happened last year after 38 years of use. @bholler can quote you current code requirements for an unlined chimney if you need the documentation.
There is an additional benefit to insulating the liner. It keeps the flue gases hotter which improves draft and decreases creosote accumulation. This can be an important plus with a catalytic stove which often has cooler flue gases.
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