Totally confused - need thimble help

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MountainDrunk

New Member
Dec 14, 2021
13
Sylva, NC
A8EF6C7E-CBA7-44A0-BB46-E1EF9F46C731.jpeg
I’m installing an old Buck stove in a 1964 brick house. Chimney is close to center of house. Stove will be installed in the living room and will vent to the existing 6” chimney flue pictured below. Original wood paneling removed. I’ll be replacing it with a wall of durock and thin brick. But it’s the stove pipe I’m confused about.

The 6” hole in the picture has 4” clearance on either side to the 2x4. I know to make that workable, I’ll need an insulated thimble. But I can’t find any reference to what type of thimble I need for this set up, the correct sizing, how it’ll be attached behind the wall and onto the chimney. My head is spinning. Probably overthinking it, but I want this done right the first time.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
28,189
central pa
View attachment 288323 I’m installing an old Buck stove in a 1964 brick house. Chimney is close to center of house. Stove will be installed in the living room and will vent to the existing 6” chimney flue pictured below. Original wood paneling removed. I’ll be replacing it with a wall of durock and thin brick. But it’s the stove pipe I’m confused about.

The 6” hole in the picture has 4” clearance on either side to the 2x4. I know to make that workable, I’ll need an insulated thimble. But I can’t find any reference to what type of thimble I need for this set up, the correct sizing, how it’ll be attached behind the wall and onto the chimney. My head is spinning. Probably overthinking it, but I want this done right the first time.
Any insulated thimble will work some attach to the chimney some you will need to frame for.

Does the chimney have an insulated liner?
 

blades

Minister of Fire
Nov 23, 2008
3,727
WI, Leroy
hate to mention this, but that existing flue will need to be lined.
 
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MountainDrunk

New Member
Dec 14, 2021
13
Sylva, NC
See now, I get nothing but conflicting info with that. While it’s the safe way to go, most of the old timers around here laughed at the prospect. Told me to hook the thing up and shut up about it 🤷‍♂️
 

kennyp2339

Minister of Fire
Feb 16, 2014
6,532
07462
So when you look down the chimney from the roof you only see concrete block or do you see tan clay liners? What size is the chimney diameter, is it rectangle, square or round?
Now if the chimney doesnt have a clay liner you will def need a stainless steel insulated liner before you can hook up a solid fuel heater to the chimney, as is, you will burn the place down, maybe not in the first few fires, but a month, two or season you will have a major issue develop.
If the chimney has clay tiles in it, you will need to inspect each tile (cell phone video tied to a rope) making sure the tiles dont have any cracks or mortar missing from joints, then you will need to determine that the chimney is free standing w/ at least 2" of clearance from any combustibles like framing, flooring. If you dont have the clearance then you will need to install an insulated liner to meet clearance.
For the thimble area, you will need to remove those wood studs and give yourself the proper clearance of 6" insulated thimble with the thimble going into the room 6" or 18" with the thimble being mounted flush, simply screwing some cement board does not reduce clearance, as clearance is taking from the nearest combustible which would be under the cement board.
 

MountainDrunk

New Member
Dec 14, 2021
13
Sylva, NC
So when you look down the chimney from the roof you only see concrete block or do you see tan clay liners? What size is the chimney diameter, is it rectangle, square or round?
Now if the chimney doesnt have a clay liner you will def need a stainless steel insulated liner before you can hook up a solid fuel heater to the chimney, as is, you will burn the place down, maybe not in the first few fires, but a month, two or season you will have a major issue develop.
If the chimney has clay tiles in it, you will need to inspect each tile (cell phone video tied to a rope) making sure the tiles dont have any cracks or mortar missing from joints, then you will need to determine that the chimney is free standing w/ at least 2" of clearance from any combustibles like framing, flooring. If you dont have the clearance then you will need to install an insulated liner to meet clearance.
For the thimble area, you will need to remove those wood studs and give yourself the proper clearance of 6" insulated thimble with the thimble going into the room 6" or 18" with the thimble being mounted flush, simply screwing some cement board does not reduce clearance, as clearance is taking from the nearest combustible which would be under the cement board.
So what do you figure the people who owned the house before me were doing with their wood stove sitting there? Wood stove had been used in that room since 1964.
 

kennyp2339

Minister of Fire
Feb 16, 2014
6,532
07462
So what do you figure the people who owned the house before me were doing with their wood stove sitting there? Wood stove had been used in that room since 1964.
There were more house fires back then, but also the masonry was prob less broken down back then since it was newer to. There's also a thing called pyrolysis, its the breakdown of wood flash point over time due to being heated and cooled multiple times, after long periods of improper exposure wood that normally ignites at say 450deg f can ignite at temps of 150deg f due to break down of wood fibers and chemical carbon change due to heat.
 
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stoveliker

Minister of Fire
Nov 17, 2019
4,353
Long Island NY
Wrong situations do not guarantee a house fire. They do, however, greatly increase the risk of one (and as pointed out, an increasing risk with time). Do you want that risk? Your insurance may note it was done incorrectly after shtf, and might give a hard time paying out. Do you want that risk?

Society learned from previous shtf cases. You can disregard that knowledge. But it's at your own peril.
 

MountainDrunk

New Member
Dec 14, 2021
13
Sylva, NC
Wrong situations do not guarantee a house fire. They do, however, greatly increase the risk of one (and as pointed out, an increasing risk with time). Do you want that risk? Your insurance may note it was done incorrectly after shtf, and might give a hard time paying out. Do you want that risk?

Society learned from previous shtf cases. You can disregard that knowledge. But it's at your own peril.
Oh I understand. The last guy who told me he paid to have his chimney lined with stainless said he paid 6k. I held off buying a stove for super cheap so I could refurbish it myself and save money. If I find a lining is required, there will never be a stove in my house, unfortunately.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
28,189
central pa
Oh I understand. The last guy who told me he paid to have his chimney lined with stainless said he paid 6k. I held off buying a stove for super cheap so I could refurbish it myself and save money. If I find a lining is required, there will never be a stove in my house, unfortunately.
I can tell You without question your current chimney does not meet minimum safety codes. For your internal masonry chimney to meet code you need 2" clearance to combustible materials from the outside of the masonry structure for use with solid fuel. Yes you could hook it up and it may be fine. It also may cause a fire there is no way to know until it's too late
 

NickW

Minister of Fire
Oct 16, 2019
722
SE WI
Lining a chimney isn't difficult. I installed a brand new NC30 stove and an insulated liner in '19 myself for about $2500. Liner cost more than the stove.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
28,189
central pa
Lining a chimney isn't difficult. I installed a brand new NC30 stove and an insulated liner in '19 myself for about $2500. Liner cost more than the stove.
It isn't difficult in some cases and is extremely difficult in others.
 

begreen

Mooderator
Staff member
Nov 18, 2005
92,817
South Puget Sound, WA
See now, I get nothing but conflicting info with that. While it’s the safe way to go, most of the old timers around here laughed at the prospect. Told me to hook the thing up and shut up about it 🤷‍♂️
Same folk that say burn hot enough to have an occasional chimney fire to clean the flue out? Venting into a cold unlined chimney is a good way to build up creosote and tempt fate.

Here is an article on the topic of a safe thimble:

The issue of needing a liner for safety and better stove operation is well documented. Feel free to ask questions on that topic too if you need any help.
 

MountainDrunk

New Member
Dec 14, 2021
13
Sylva, NC
Same folk that say burn hot enough to have an occasional chimney fire to clean the flue out? Venting into a cold unlined chimney is a good way to build up creosote and tempt fate.

Here is an article on the topic of a safe thimble:

The issue of needing a liner for safety and better stove operation is well documented. Feel free to ask questions on that topic too if you need any help.
So the chimney has a clay liner. I’ve got a guy coming to do an inspection Monday. I’ll know more then.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
28,189
central pa
So the chimney has a clay liner. I’ve got a guy coming to do an inspection Monday. I’ll know more then.
It doesn't meet code for a clay lined chimney because it clearly doesn't have the required 2" clearance to combustibles.
 
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blades

Minister of Fire
Nov 23, 2008
3,727
WI, Leroy
good. better safe than sorry. going back aways the chimney's of the era were fine for there intended purposes, mostly gas or oil heat. the problem in various areas, maybe not so much in your climate, was the dampness in the spring and fall combined with wild swing in temp creating condensation in the flue. combine that with byproducts of combustion and a acid would be formed eating away at the mortar joints. Back in the day most heating furnaces and hot water heaters had a standing pilot light, that little bit of heat tended to ward off the condensation. fast forward to the on demand units and 90-95% units- no pilot light and problems began to appear. 3 of the 4 homes that I owned being built prior to the 70's required repairs for this. the last one was a 1959-60 build and that required busting out the clay tiles and new liner installed. $ ouch.
 

MountainDrunk

New Member
Dec 14, 2021
13
Sylva, NC
So the inspection/sweep is completed. The tech said my chimney is in excellent shape, and was extremely well built. We talked about newer codes requiring 2” clearance between masonry and flammables. His reply was that if everyone in the area was required to confirm to that, 75% of the wood stoves in my area would be shut down. Considering my clay insert tiles and masonry are in great shape, im going to “roll the dice” as it were.

That still leaves the problem of the 6” access hole, and the rectangle to round converter coming from the Buck being 8”. I’ve talked to a couple stove shops in the area who said I’d likely not have a problem. The interior of the chimney is 12x12, tapered slightly at the top. But I wonder, what might be the downside of hiring a mason to increase the access from 6” to 8”? Any thoughts?
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
28,189
central pa
So the inspection/sweep is completed. The tech said my chimney is in excellent shape, and was extremely well built. We talked about newer codes requiring 2” clearance between masonry and flammables. His reply was that if everyone in the area was required to confirm to that, 75% of the wood stoves in my area would be shut down. Considering my clay insert tiles and masonry are in great shape, im going to “roll the dice” as it were.

That still leaves the problem of the 6” access hole, and the rectangle to round converter coming from the Buck being 8”. I’ve talked to a couple stove shops in the area who said I’d likely not have a problem. The interior of the chimney is 12x12, tapered slightly at the top. But I wonder, what might be the downside of hiring a mason to increase the access from 6” to 8”? Any thoughts?
To be clear these are not new codes they have been in place since the early 80s and they were put in place because there were to many fires caused by heat transfer without the clearances.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
28,189
central pa
Btw durarock and brick will not reduce the clearances to the wall framing
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
28,189
central pa
Correct, but it will remove wood paneling as a flammable to the stove. So what reduces the clearance between the stove itself, and the framing behind the durock and brick?
A properly built NFPA heat sheild.
 

thewoodlands

Minister of Fire
Aug 25, 2009
14,586
Foothills of The Adirondacks
So the inspection/sweep is completed. The tech said my chimney is in excellent shape, and was extremely well built. We talked about newer codes requiring 2” clearance between masonry and flammables. His reply was that if everyone in the area was required to confirm to that, 75% of the wood stoves in my area would be shut down. Considering my clay insert tiles and masonry are in great shape, im going to “roll the dice” as it were.

That still leaves the problem of the 6” access hole, and the rectangle to round converter coming from the Buck being 8”. I’ve talked to a couple stove shops in the area who said I’d likely not have a problem. The interior of the chimney is 12x12, tapered slightly at the top. But I wonder, what might be the downside of hiring a mason to increase the access from 6” to 8”? Any thoughts?
What does your insurance company say?