[Help] Wood stove pipe through new basement wall

[orangeisnon]

Hello,
Looking for some advice for re-installing my wood stove. We are semi-finishing the basement and are putting a wall up between the existing masonry chimney and the stove. This is to section off the area where the oil-burning hot water heater and my work benches are from the rest of the basement (planned den/recreation area). The chimney is located at roughly the center of the basement. I built the section of wall between the stove and chimney out of cement board since it is not combustible, and spaced out the studs so there are no combustibles near where the pipe needs to go through the wall.
My stove uses 6" pipe and my chimney has a 7" opening. Prior to building the wall, I have been using normal 6" stove pipe and a 6" to 7" adapter to connect the two. This worked great, and with my almost 30 foot chimney I have always had great draft and no smoke leaking out of the connections. We have a small stove that is only used for supplemental heat in the basement and only runs a handful of days a month - though I expect this to change once the basement is more fleshed out.

My issue is that I am unsure of the best/safest way to route the stove pipe through the wall. I have a 6" Selkirk 206463 wall thimble that I had intended to use, however the opening in the thimble is made for a larger pipe. I believe double-wall chimney pipe, based on measurements I have found online. The instructions that come with the thimble are useless.
As I see it, my options are:
1. Cut a ~6" hole in the cement board, tile around it, send the stove pipe through with a trim collar, connect and call it a day.
2. Install the thimble and use a short section of chimney pipe along with a handful of adapters to go from stove pipe to chimney pipe back to stove pipe to chimney.
3. Install the thimble and send the stove pipe through, potentially with some kind of fireproof insulation around it to fill the gap.
#1 would be easiest but I am definitely concerned about the safety of it. Cement board is non-combustible but I'm still not sure it is safe to have it right up against a hot single-wall stove pipe. Maybe use 6" double-wall for this?
#2 seems like the "right" way to do it, though I don't know if the adapter I need to go from chimney back to stove pipe even exists, or if there is another fitting that is supposed to be used to go from steel chimney pipe to a 7" masonry opening.
#3 gives a nice compromise between the two but would be the least visually appealing. I suppose I could use a trim collar to cover the gap, but I'm still not sure this is the best way to do it.
Any thoughts?

 

[bholler]

Hello,
Looking for some advice for re-installing my wood stove. We are semi-finishing the basement and are putting a wall up between the existing masonry chimney and the stove. This is to section off the area where the oil-burning hot water heater and my work benches are from the rest of the basement (planned den/recreation area). The chimney is located at roughly the center of the basement. I built the section of wall between the stove and chimney out of cement board since it is not combustible, and spaced out the studs so there are no combustibles near where the pipe needs to go through the wall.
My stove uses 6" pipe and my chimney has a 7" opening. Prior to building the wall, I have been using normal 6" stove pipe and a 6" to 7" adapter to connect the two. This worked great, and with my almost 30 foot chimney I have always had great draft and no smoke leaking out of the connections. We have a small stove that is only used for supplemental heat in the basement and only runs a handful of days a month - though I expect this to change once the basement is more fleshed out.

My issue is that I am unsure of the best/safest way to route the stove pipe through the wall. I have a 6" Selkirk 206463 wall thimble that I had intended to use, however the opening in the thimble is made for a larger pipe. I believe double-wall chimney pipe, based on measurements I have found online. The instructions that come with the thimble are useless.
As I see it, my options are:
1. Cut a ~6" hole in the cement board, tile around it, send the stove pipe through with a trim collar, connect and call it a day.
2. Install the thimble and use a short section of chimney pipe along with a handful of adapters to go from stove pipe to chimney pipe back to stove pipe to chimney.
3. Install the thimble and send the stove pipe through, potentially with some kind of fireproof insulation around it to fill the gap.
#1 would be easiest but I am definitely concerned about the safety of it. Cement board is non-combustible but I'm still not sure it is safe to have it right up against a hot single-wall stove pipe. Maybe use 6" double-wall for this?
#2 seems like the "right" way to do it, though I don't know if the adapter I need to go from chimney back to stove pipe even exists, or if there is another fitting that is supposed to be used to go from steel chimney pipe to a 7" masonry opening.
#3 gives a nice compromise between the two but would be the least visually appealing. I suppose I could use a trim collar to cover the gap, but I'm still not sure this is the best way to do it.
Any thoughts?

How far are the studs from the thimble area?

 

[orangeisnon]

How far are the studs from the thimble area?

They are 36" apart, the chimney opening is dead centered between them. The instructions for the thimble go back and forth between saying that the wall should absolutely NOT be framed and talking about framing as if it is definitely there. I opted to be safer and frame as far away as I could without making the wall floppy. The wall isn't done so I can always change that if needed.

 

[kborndale]

They are 36" apart, the chimney opening is dead centered between them. The instructions for the thimble go back and forth between saying that the wall should absolutely NOT be framed and talking about framing as if it is definitely there. I opted to be safer and frame as far away as I could without making the wall floppy. The wall isn't done so I can always change that if needed.

Why not just frame with metal studs?

 

[bholler]

The right way to do this is with an insulated thimble through the wall. It can be done with class a chimney but that is a pain. It could also be done out of masonry but that needs 12" of solid masonry around the pipe going through the wall. So it's a pain as well

 

[stoveliker]

I don't understand the "back to stove pipe" issue; after going thru a wall (or ceiling), it should always be (remain) class A? Once you go to class A, there is no going back to stove pipe, in my understanding.

 

[orangeisnon]

I don't understand the "back to stove pipe" issue; after going thru a wall (or ceiling), it should always be (remain) class A? Once you go to class A, there is no going back to stove pipe, in my understanding.

I say "back to stove" because I have been unable to find an adapter that will go from the 6" chimney pipe (Class A) to my existing masonry chimney with a 7" opening. I already have a 6" to 7" stove pipe adapter so I know it exists.

The right way to do this is with an insulated thimble through the wall. It can be done with class a chimney but that is a pain. It could also be done out of masonry but that needs 12" of solid masonry around the pipe going through the wall. So it's a pain as well

I definitely don't want to start dealing with installing new masonry. I am fine with spending the money on Class A chimney pipe but need to be able to connect that to my existing chimney, and preferably be able to disconnect it for regular cleaning.

Why not just frame with metal studs?

In my area metal studs are much more expensive than wood and I am not familiar with working with them. I have all of the tools required for wood framing and have a pile of 2x4's as tall as me in the basement, so I'm sticking with that. With that said I would be fine with throwing a couple metal studs up to support the thimble if that is necessary - the problem is the instructions that came with the thimble aren't clear as to whether they should be secured to framing or not and I don't want to do anything that could end up causing damage.

Thanks for all the replies, guys.

 

[bholler]

I say "back to stove" because I have been unable to find an adapter that will go from the 6" chimney pipe (Class A) to my existing masonry chimney with a 7" opening. I already have a 6" to 7" stove pipe adapter so I know it exists.

I definitely don't want to start dealing with installing new masonry. I am fine with spending the money on Class A chimney pipe but need to be able to connect that to my existing chimney, and preferably be able to disconnect it for regular cleaning.

In my area metal studs are much more expensive than wood and I am not familiar with working with them. I have all of the tools required for wood framing and have a pile of 2x4's as tall as me in the basement, so I'm sticking with that. With that said I would be fine with throwing a couple metal studs up to support the thimble if that is necessary - the problem is the instructions that came with the thimble aren't clear as to whether they should be secured to framing or not and I don't want to do anything that could end up causing damage.

Thanks for all the replies, guys.

To do class a chimney you would typically open up the chimney enough to fit the class a into it then mortar it in. But an insulated thimble made for a masonry chimney is definitely the easiest way to go. I really like the ventis one

 

[orangeisnon]

To do class a chimney you would typically open up the chimney enough to fit the class a into it then mortar it in. But an insulated thimble made for a masonry chimney is definitely the easiest way to go. I really like the ventis one

I did some searching and I think you are referring to the adapter that lets you connect 6" double-wall pipe to a masonry chimney (Ventis VDB06MA). I found the installation guide for that and agree that I should definitely have one of those in the chimney. With that said, is it safe to run double-wall stove pipe through my cement board wall with just a slightly larger hole and a trim collar? I still need to get through the "wall" AKA single sheet of cement board, eventually tiled.

 

[bholler]

I did some searching and I think you are referring to the adapter that lets you connect 6" double-wall pipe to a masonry chimney (Ventis VDB06MA). I found the installation guide for that and agree that I should definitely have one of those in the chimney. With that said, is it safe to run double-wall stove pipe through my cement board wall with just a slightly larger hole and a trim collar? I still need to get through the "wall" AKA single sheet of cement board, eventually tiled.

No I am talking about an insulated wall thimble.

https://www.shop.com/OLYMPIA+CHIMNEY+VENTING+6+Insulated+Wall+Thimble+for+22+Tee+Connection+ITH06+T-1904988428-p+.xhtml

 

[orangeisnon]

No I am talking about an insulated wall thimble.

https://www.shop.com/OLYMPIA+CHIMNEY+VENTING+6+Insulated+Wall+Thimble+for+22+Tee+Connection+ITH06+T-1904988428-p+.xhtml

Thanks for the clarification. I read the installation guide for that, and it looks good, except that it only extends to 14" and my wall is 18" from the chimney. I will look for other manufacturers, maybe one has a longer unit.

 

[bholler]

Thanks for the clarification. I read the installation guide for that, and it looks good, except that it only extends to 14" and my wall is 18" from the chimney. I will look for other manufacturers, maybe one has a longer unit.

I know they will make custom lengths but another company may very well have a longer one

 

[orangeisnon]

I think I might be overthinking this. As far as I can tell, there is no clearance requirement for non-combustible materials, regardless of what kind of stove pipe is used. My wall is non-combustible. If I use double-wall stove pipe, I think I can go right through the cement board and maintain a safe distance from my ~15" away wooden studs. Then use a DSP masonry adapter at the chimney opening.
Does this sound wrong to anyone?

 

[stoveliker]

As far as I know,.you can only use stove pipe up to a penetration (wall or ceiling), not beyond. That is not a combustible issue but a safety one (stove pipe being used out of sight).

 

[orangeisnon]

As far as I know,.you can only use stove pipe up to a penetration (wall or ceiling), not beyond. That is not a combustible issue but a safety one (stove pipe being used out of sight).

Interesting, and makes sense. I wonder if I could put a small window in nearby.
Here's a very basic diagram of what I want to do. It's not to scale, there is ~10 feet from the front of the stove to the foundation wall. But I will have a corner that I could legitimately install a window into to keep an eye on the pipe from the side.

C=Chimney, HW=Hot Water heater,WS=Wood Stove
The chimney has two separate clay-lined flues, I am not dumping the wood stove exhaust into the same flue as the water heater.

 

[bholler]

I think I might be overthinking this. As far as I can tell, there is no clearance requirement for non-combustible materials, regardless of what kind of stove pipe is used. My wall is non-combustible. If I use double-wall stove pipe, I think I can go right through the cement board and maintain a safe distance from my ~15" away wooden studs. Then use a DSP masonry adapter at the chimney opening.
Does this sound wrong to anyone?

Connector pipe cannot pass through a wall period. Combustible or not it can't be done according to code. And your wall isn't non-combustible if it has wood framing

 

[orangeisnon]

Connector pipe cannot pass through a wall period. Combustible or not it can't be done according to code. And your wall isn't non-combustible if it has wood framing

That's fair. That's why I came here instead of just slapping it together. I will keep looking into those thimbles you brought up.
Though for the record, what I am going for is "not going to burn my house down", not "will make the town building inspector happy".

 

[bholler]

That's fair. That's why I came here instead of just slapping it together. I will keep looking into those thimbles you brought up.
Though for the record, what I am going for is "not going to burn my house down", not "will make the town building inspector happy".

You also need to worry about will my insurance pay if something goes wrong

 

[orangeisnon]

Thanks again for the insight. I ended up using a 36" section of double wall stove pipe (Selkirk DSP6P36-1) going through a thimble (Selkirk 6T-IWT) extended using 2 pieces of 6" single wall stove pipe connected together to make a 12" diameter pipe, packed with a 1"x24"x60" ceramic fire blanket, with a masonry adapter (Selkirk DSP6MA) to connect the double wall pipe into the chimney. Using the double wall alone reduced clearance to combustibles to 6". I read the fire code document and confirmed that routing connector pipe through a wall is allowed so long as it is routed through an insulated metal thimble.
I don't have any connection to Selkirk, it's just the most readily available at hardware stores in my area.
For some real-world numbers, I have been running a fire for the last 6 hours, with the outside temperature of the stove pipe coming directly out of the stove being above 600 degrees F. The outside temperature of the thimble has remained within 10 degrees of ambient air temperature. It feels cold to the touch. (I'm using an infrared non-contact thermometer, a proper flue thermometer is coming soon)