Freestanding in front of FP....double or single wall connecting pipe?

[Adahn]

From an earlier thread, I bit the bullet and had an insulated liner installed for the new Fireview.
Setup is ~33', 6" heavy flex, with insulated wrap, and metal mesh, inside 120y.o. masonry chimney. They got it winched up to the cap with a single wall T at the bottom (with cleanout) and horizontal hookup to the Fireview. In retrospect, was there any reason to push for double wall/close clearance connecting stovepipe (i.e. Ventis or similar)? Fireplace is interior/ central to house. The wall of the room behind it is drywalled with an airspace.
How does the 18" clearance stat for single wall stovepipe (vs 6" for double) translate to a masonry FP install?

The thing draws like a champ. How would I know if I need a damper?

 

[begreen]

Chimney and chimney liner clearances are a different animal from stove pipe. Stove pipe which is out in the room envelope and can not penetrate floors or walls. In a chimney there is a layer of masonry between the liner and combustibles. If there is an air space all around the chimney all the way up through the structure and roof then that is an additional layer of insulative protection. The problem is that this gap is rarely done all the way through the building, especially if there have been changes and renovations during the life of the chimney. If the chimney has no tile liner then it is a greater risk as mortar and bricks degrade over time. I removed our 80 yr old fireplace and there were many bricks in the chimney that pulled out by hand. So for a 120 y.o. chimney an insulated liner is a good idea.

33ft is a tall flue. I would ask Woodstock tech support about adding the stack damper.

 

[Adahn]

33ft is a tall flue. I would ask Woodstock tech support about adding the stack damper.

Will do.

What about the T-pipe? Is single wall considered sufficient for an interior fireplace install?

 

[bholler]

Yes it should be fine as long as you have 18" to any combustibles

 

[Adahn]

Yes it should be fine as long as you have 18" to any combustibles

I also read 12" if through masonry with an airspace. How thick should I assume the back of the brick fireplace firebox is?

 

[bholler]

Where was that and what was it referring to? If it was a working fireplace built with proper clearances you are perfectly safe was it inspected?

 

[fossil]

I don't think you have any problem at all with the single-wall Tee in that installation. Sounds like, with the full-height insulated liner to daylight you've done everything right (I'm assuming you have a block-off plate installed). I'd only think about installing a damper if the draft seems to be a problem/uncontrollable. Get to know the system as is for a while before you contemplate any mods. Rick

 

[Adahn]

Listed in the Woodstock manual for NFPA 211 standards ...stovepipe 12" to combustibles through masonry 3.5" plus 1" airspace. Inspection this week.

 

[fossil]

Does the Tee actually penetrate and pass through masonry, or just reside behind the stove in the fireplace?

 

[Adahn]

Behind, hooked straight to bottom of liner.

 

[bholler]

You should be just fine but if it worries you have it inspected by a certified sweep

 

[fossil]

I think you're good to go. Rick

 

[bholler]

I concur with fossil

 

[Adahn]

Good to hear. Thanks all for the advice.