noob question about connections

  • 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.

offgridsomewhere

New Member
Oct 14, 2022
6
Central Virginia
I have a block interior chimney that I am trying to update. It used to have an 8x8 clay liner, but it was badly cracked. I have a single-walled 6" flexible steel liner with a tee connector on hand already, which only fit down the chimney after breaking off the clay liner. I am planning on insulating the new liner with a 1/2" insulation blanket since there is now plenty of space in the chimney, and it is pretty straight. However, I am unsure of what to use for a safe connection to a stove pipe. The chimney is situated in the middle of a drywall partition between the kitchen and living room, with drywall almost sitting flush with the center of the block. There is no masonry crock where the old stove pipe connected to the chimney; just a hole punched through the block (I am guessing it used to have a crock, considering there is another chimney elsewhere in the house in the same condition that does have one...). I am assuming that I can't use a double walled masonry adapter (something like this) because the block does not extend 6" from the perimeter of the hole in all directions. Because the chimney is unlined and so close to combustibles, should I be looking at an insulated thimble such as this even though the connection isn't technically through a combustible wall?
 
Outside of the drywall, which has combustible paper on it, how close are the other nearestcombustibles, like studs, to the tee snout?
 
On the left side the only nearby combustible is the stud that the drywall panel is nailed to, 16” away. On the right side there is a piece of trim on the wall that actually runs along the chimney up to the ceiling, and then maybe an inch from that is a door frame. There is maybe 2 or 3 inches between the outside perimeter of the hole where snout would exit the chimney and the edge of the chimney blocks.
 
For a clay liner thimble there needs to be a minimum of 12" of masonry between the clay liner and wall combustibles. A short section of 6" insulated class A chimney pipe could be used instead. The insulated thimble is also ok. bholler may have another suggestion.
 
You mean use a piece of chimney pipe as an improvised insulated thimble, basically? If the chimney pipe is 6" ID, is it possible to fit the snout in? Also, would you do anything to the chimney pipe to keep it in place, like mortar it, or would it be fine just sitting in the hole in the chimney?
 
The thimble should be secured to the masonry either mechanically or at least mortared in.
 
You mean use a piece of chimney pipe as an improvised insulated thimble, basically? If the chimney pipe is 6" ID, is it possible to fit the snout in? Also, would you do anything to the chimney pipe to keep it in place, like mortar it, or would it be fine just sitting in the hole in the chimney?
No a 6" thimble won't fit through a piece of 6" class a chimney if I am using class a I usually use a section of 7" class a. But an insulated thimble is absolutely the proper way to do it.