Building house - need advice on SS liner vs clay tile

[dznam]

Well, having burned wood for 35 years and reading these forums regularly for years, I thought I knew everything about woodstoves (not) . I was hoping you guys could help me out with a question that has me flummoxed...

Background:

We're building our retirement house here in ME and are putting in a 2 flue brick chimney - one for the dino burner and another for the wood stove. The stove is going on a hearth on an outside wall. with the first 7 feet of the 28' chimney running inside the building envelope (2nd floor has smaller footprint than 1st floor). The will be no fireplace, jI was planning on just a thimble in the brick facade. There is a full basement under the hearth). We have not sized the flue for the stove yet, but (at a minimum) it'll accomodate our Keystone stove with a 7" exit pipe.

Question:

Is there an intelligent way to install a flexible liner in this flue? Is it necessary or desirable? (I already have a Magnaflex double wall insulated liner, so don't need to consider liner purchase price in this decision) Will it be possible to clean it and how should I construct the chimney to make cleaning easy/possible? Or would adding a liner to a new, properly sized tile flue just constitute needless complexity?

Thanks, Dznam

 

[begreen]

Yes you can do this, but it seem like overkill. If building new, why not run class A for both units and then build a chase around the pipes to hide them?

 

[jeff_t]

Yes you can do this, but it seem like overkill. If building new, why not run class A for both units and then build a chase around the pipes to hide them?

Seems silly to build a masonry chimney with the intention of lining it. Insulated class A is so much better. It's like building a fireplace to install an insert.

 

[webby3650]

If you just want a masonry chimney, it would be best to go with a rigid insulated SS liner. Skip the clay altogether.

 

[dznam]

If you just want a masonry chimney, it would be best to go with a rigid insulated SS liner. Skip the clay altogether.

I do want a masonry chimney - really don't care for the looks of "wood chimneys". Why is a class A stainless liner better than a clay tile? I was under the impression that a modern clay tile is pretty much a "forever" product while any liner or class A rigid would eventually need to be replaced - sounds like that is not the case? If it's the way to go can a masonry chimney be constructed with a class A liner? Any special considerations in doing this?

 

[fox9988]

One chimney fire "could" damage a chimney. Tiles are not repairable or replaceable. You can build a chase with class A in it, then brick around it. Much cheaper.

 

[dznam]

One chimney fire "could" damage a chimney. Tiles are not repairable or replaceable. You can build a chase with class A in it, then brick around it. Much cheaper.

Thanks for the replies - I'm starting to get the picture...

I've got a great ("friends and family") price for a full masonry build. Would it be possible to just substitute the Cl A for tile in a conventionally built chimney? Any special considerations?

 

[fox9988]

The material cost alone on a full masonry chimney should be many times more than a full price bricked chase. I've never heard of a class A in a masonry chimney. If the chimney were hollow, it probably could be done, but I can't see the advantage.

 

[clemsonfor]

Why not put a brick chase up, like an old style single brick chimney and then run either SS ridged liner or flex through it? NOt sure this is code or not but this would give the look he wants and the purpose he needs. Sized right you could put at least 2 if not 3 six inch SS liners in there. I too hate the was wood sided or vinyl chimneys look.

 

[dznam]

The material cost alone on a full masonry fire place should be many times more than a full price bricked chase. I've never heard of a class A in a masonry chimney. If the chimney were hollow, it probably could be done, but I can't see the advantage.

Thanks, looks like I'll be talking with the mason this week and I'll see what he has to say.

 

[weatherguy]

Your already building a chimney for the furnace right? I would think it would look much better to have it all brick with a liner inside. I go through this in my head for the next house Im going to build, if I build a chimney for the furnace that I hope to never use I would think the way to do a flue for a woodstove would be to build it together right next to it.
Let me know what you end up finding out, it will be valuable info for my future home.

 

[webby3650]

In this instance, what you need to do is have a SS liner installed, not class A. The brick chimney will have a block core, that is hollow, that is were the flue will be. Instead of building it up with clay liners, they will use SS rigid liner sections instead. After it's done, a special insulation can be poured down around the SS liner. The mason probably won't be familiar with this procedure. Get a local, Reputable, chimney sweep involved. SS is the way to go, clay flues are a thing of the past.

 

[DaveGunter]

In this instance, what you need to do is have a SS liner installed, not class A. The brick chimney will have a block core, that is hollow, that is were the flue will be. Instead of building it up with clay liners, they will use SS rigid liner sections instead. After it's done, a special insulation can be poured down around the SS liner. The mason probably won't be familiar with this procedure. Get a local, Reputable, chimney sweep involved. SS is the way to go, clay flues are a thing of the past.

Not wanting to hijack this thread, but this is what I am dealing with right now. I am burning in an 30nc in my basement, hooked to one of two clay lined flues in a dual flue chase. The chimney from thimble to top is about 35 feet, the chimney is internal against an outside wall through two floors of living space and then through about 9 feet of attic. Yesterday was warm (40*) so I let the stove go out overnight the night before and inspected the flue yesterday and could see buildup. So far this year I have burned about 2.5 cords of DRY white birch and red maple. I ran a brush down the chimney and got about 3 gallons of black chunky creosote, 95% of which was in the top half of the flue. This is similar to the year before when I was burning less than optimal wood in an "airtight smoke dragon". After seeing the buildup last year I decided to switch to the 30nc hoping things would be better with a more efficient burn with properly seasoned and dry wood. It doesn't seem to be the case. The flue is just too tall and the gasses are still condensing esp where the flue runs through the cold attic, even though I am conscience about burning hot fires. My single wall pipe temp is never below 350* at 18" above the stove during an active burn, it does go below that during coaling, but I can't make it be higher even with the stove air all the way open.

So what do I do?

-Insulate the outside of the chimney where it runs through the attic? Is there a way to do this safely...is it really going to help much?

-Add a liner. The clay liner is 8" square OD, so the ID is about 7". Is there a liner that will fit and insulate the well enough and still give enough draft for a big stove. How does the liner attach to the thimble...can there still be a T there so when I do have to clean the flue the creosote can be cleaned out below the thimble.

-Just deal with it and realize that I need to sweep the flue every 4-6 weeks...what happens if the winter is bad and I can't access the flue from the roof due to snow buildup. Yesterday when I cleaned I pushed the brush down from the roof with the rods I have and then pulled it the rest of the way with an attached rope. Pushing the bush with my rods became tough after about 20 feet...too much bend in the rods.

I'm leaning toward the liner because it seems to be the best permanent fix, but I know nothing about what is available and how to install them.

 

[webby3650]

7"? Well, if the clay liners are all lined up good, a 6" liner with a 1/4" insulation blanket might go. It might not too. Since it's 35' tall, a 5.5" liner would probably do OK. The Tee will be 2 pieces, the body is attached to the liner and the snout is secured to it trough the thimble. It must have a cap on the Tee. After you sweep it, remove the stove pipe to clean out the bottom of the Tee.

 

[dznam]

Not wanting to hijack this thread, but this is what I am dealing with right now. I am burning in an 30nc in my basement, hooked to one of two clay lined flues in a dual flue chase. The chimney from thimble to top is about 35 feet, the chimney is internal against an outside wall through two floors of living space and then through about 9 feet of attic. Yesterday was warm (40*) so I let the stove go out overnight the night before and inspected the flue yesterday and could see buildup. So far this year I have burned about 2.5 cords of DRY white birch and red maple. I ran a brush down the chimney and got about 3 gallons of black chunky creosote, 95% of which was in the top half of the flue. This is similar to the year before when I was burning less than optimal wood in an "airtight smoke dragon". After seeing the buildup last year I decided to switch to the 30nc hoping things would be better with a more efficient burn with properly seasoned and dry wood. It doesn't seem to be the case. The flue is just too tall and the gasses are still condensing esp where the flue runs through the cold attic, even though I am conscience about burning hot fires. My single wall pipe temp is never below 350* at 18" above the stove during an active burn, it does go below that during coaling, but I can't make it be higher even with the stove air all the way open.

So what do I do?

-Insulate the outside of the chimney where it runs through the attic? Is there a way to do this safely...is it really going to help much?

-Add a liner. The clay liner is 8" square OD, so the ID is about 7". Is there a liner that will fit and insulate the well enough and still give enough draft for a big stove. How does the liner attach to the thimble...can there still be a T there so when I do have to clean the flue the creosote can be cleaned out below the thimble.

-Just deal with it and realize that I need to sweep the flue every 4-6 weeks...what happens if the winter is bad and I can't access the flue from the roof due to snow buildup. Yesterday when I cleaned I pushed the brush down from the roof with the rods I have and then pulled it the rest of the way with an attached rope. Pushing the bush with my rods became tough after about 20 feet...too much bend in the rods.

I'm leaning toward the liner because it seems to be the best permanent fix, but I know nothing about what is available and how to install them.

The liner you're looking for is made by Magnaflex. It's a SS/Ti inner liner insulated and encased by another, outer casing. Have one in my home now for exactly the same reason you're describing and solved my upper chimney creosote problem.

 

[brian89gp]

A brick chimney without the clay liner and an insulated SS flex liner would probably be the cheapest way.

Why not put a brick chase up, like an old style single brick chimney and then run either SS ridged liner or flex through it? NOt sure this is code or not but this would give the look he wants and the purpose he needs. Sized right you could put at least 2 if not 3 six inch SS liners in there. I too hate the was wood sided or vinyl chimneys look.

It is permissible by code at least around here, there are different clearances to combustibles but that is about it. Also, you to have 2 or 3 SS liners you will need 2 or 3 brick chases in your chimney, they are not allowed to share a single chase.

 

[webby3650]

A brick chimney without the clay liner and an insulated SS flex liner would probably be the cheapest way.

In this instance, rigid should be used, not flex. Flex is great for a re-line but it can be damaged. When it's used to re-line, it can be removed if necessary. When the liner is used in place the of clay, it won't be removable nor would rigid ever need to be removed. Rigid would make a much more durable, permanent set-up.