Liner in existing chimney, or new Class A chimney?

drussell

New Member
Sep 22, 2020
4
NW Ohio
Ok, first post here, so bear with me.

I am trying to figure out the best way to install our Avalon Olympic wood stove at our new 1960s ranch home. It has a 2-flue masonry chimney right up the middle of the house, close to where we want to put the stove. The west flue is 6.5"x11ish ID and is connected to the basement fireplace (which we don't use currently). The east flue is 7"x7" ID and is unused (I think it used to be connected to the furnace before they upgraded it). Both are lined with terracotta tiles. We want to put the wood stove on the east side of the chimney on the main level, which is convenient since the east flue is open. (It's about 10 feet from the top of the chimney to where we would enter the chimney with the thimble.)

However, after looking into it more (especially on this site, which is why I am now posting my own question here), it looks like my options are limited. The Olympic stove requires a 6" chimney, which would be perfect if the chimney was in good shape. However, after putting a camera down the flue, it doesn't appear the tiles are in great shape: there's small chunks missing from the tiles and some mortar that is missing (or at least it appears that way on the camera: it was hard to see for sure). On top of that, the chimney itself has 0 airspace to combustibles (in the attic, the rafters and ceiling joists are all right up to it). Now, I've seen some varying opinions on how necessary that airspace is, so please chime in.

So it seems that I'm going to need a liner. However, it appears through my research that a 6" flex liner won't fit very well down a 7"x7" clay flue liner, especially if the tiles aren't lined up perfectly and/or there is some mortar sticking out, which there is. (It is a straight run down, so that helps.) A rigid 6" liner seems a little iffy too, but more so because of the snout-less tee you have to shove down there. And even if it did fit, because the chimney has 0 airspace to combustibles, it seems that an insulated liner is required? But because of the tight fit already, it seems that I wouldn't be able to get enough insulation down there even with the stuff you pour in the space after it's installed.

So unless the airspace issue isn't a problem, it appears the only way to use the 7x7 flue with the Olympic is to tear out the clay tile. That seems a little extreme, and I'm not terribly interested in doing that. I'd rather put another Class A chimney up. But then since it would be close to the existing chimney, not only would it look dumb from the outside to have two close together (maybe it wouldn't, I don't know), now the new chimney would have to be 2 feet higher than the old one, which would make it look even worse. Unless, of course, we took down the old chimney, which seems extreme too. One advantage of the class A chimney is that we could go straight up from the stove. If we used the existing chimney, we are going to have a couple feet horizontal offset in the stove pipe just because of where we want the stove.

I feel like I'm in a pickle and I need some good common sense advice on how to proceed. Any thoughts?
 

begreen

Mooderator
Staff member
Nov 18, 2005
84,325
South Puget Sound, WA
It's a common pickle. Busting out the tiles is the usual solution and not that big a deal to a sweep used to doing this. How tall is the chimney from this 1st floor room? Are you think of using the basment fireplace at some later time? If not, it could be decommissioned and an oval liner put down for the Olympic. Or more radically, all the masonry could be removed and a class A chimney with a ceiling support box put in that place.
 

drussell

New Member
Sep 22, 2020
4
NW Ohio
When I was measuring how much liner I would need, I measured 10' from the top of the clay tile to where the thimble would go thru the wall (about 12 or so inches from the main floor ceiling).

We are not currently planning on using the basement fireplace, but I'd rather keep that option open (or at least the option of using that flue for a stove downstairs for some reason). Plus, that flue is on the opposite side of the chimney of where we want to put the stove, so it would harder to use that flue.
 

Highbeam

Minister of Fire
Dec 28, 2006
17,681
Mt. Rainier Foothills, WA
Your choice looks pretty clear. Spend money on renovating the 7x7 or install a third flue using class A pipe. I have seen plenty of pipe chimneys beside masonry chimneys and it actually looks a little better to me when it's farther away. This also allows you to properly roof between the two.

I don't like masonry chimneys to start with so would vote for the class A pipe before spending any more money on that non code comnpliant, dangerous, dinosaur.

Another factor is whether you might want to use the 7x7 in the future for a furnace, water heater, or whatever in the basement. You know, the other flue for the basement fireplace is probably in bad shape too and you know that the chimney is not built properly being up against the wood.

Maybe rip the whole masonry thing out and install two class A flues.
 

vwmike

Feeling the Heat
Oct 7, 2013
321
Chilliwack, BC, Can.
I used to be hung up on masonry chimneys and think they where better and class A chimneys where cheap. After living in my current house which had a class A when I moved in, I would never look back, they draft better, stay way cleaner, and in my opinion are safer.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
22,181
central pa
There is absolutely nothing wrong with a masonry chimney with an insulated liner. Prefab chimneys really offer no safety benefit over a properly lined masonry chimney. The benefit is that it is much easier to come straight off the stove with a prefab which gives a performance benefit. It is also much easier to place the stove where ever you want. But I do prefer the look of masonry
 

begreen

Mooderator
Staff member
Nov 18, 2005
84,325
South Puget Sound, WA
There is absolutely nothing wrong with a masonry chimney with an insulated liner. Prefab chimneys really offer no safety benefit over a properly lined masonry chimney. The benefit is that it is much easier to come straight off the stove with a prefab which gives a performance benefit. It is also much easier to place the stove where ever you want. But I do prefer the look of masonry
In an earthquake-prone area, I will go with a properly installed metal chimney any day.
 
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bholler

Chimney sweep
Staff member
Jan 14, 2014
22,181
central pa
In an earthquake-prone area, I will go with a properly installed metal chimney any day.
True I don't have to deal with that in our area. And it isn't much of a danger in Ohio. But it is certainly a consideration in some areas
 

begreen

Mooderator
Staff member
Nov 18, 2005
84,325
South Puget Sound, WA
Yes, I think that is where Highbeam is coming from. When the earth starts rolling in waves, things move about a lot if they are not anchored down. Weaker masonry joints fracture. Our chimney top broke off and rotated 45º, held in place only by the rigid liner.
 
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Highbeam

Minister of Fire
Dec 28, 2006
17,681
Mt. Rainier Foothills, WA
Earthquakes are not a primary concern of mine but that can be another cause for the cracks, leaks, and failure of using a very expensive stack of rocks for a chimney. Masonry chimneys are obsolete in many ways but with an insulated liner inside you can certainly make use of it. At that point the ultra expensive rock stack is just there to support the steel pipe liner.

Aesthetically they can be beautiful works of art. I think we all can appreciate superb craftsmanship.

To me there are many reasons to not want a masonry chimney but nothing in the pro column other than aesthetics which is subjective. Is there any advantage? If I bought a house with a masonry stack in great condition that was well built, in great shape, not leaking, had an insulated liner that matched my stove, I would certainly use it.

I personally wouldn’t build a new one or put much money into an old one.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
22,181
central pa
Earthquakes are not a primary concern of mine but that can be another cause for the cracks, leaks, and failure of using a very expensive stack of rocks for a chimney. Masonry chimneys are obsolete in many ways but with an insulated liner inside you can certainly make use of it. At that point the ultra expensive rock stack is just there to support the steel pipe liner.

Aesthetically they can be beautiful works of art. I think we all can appreciate superb craftsmanship.

To me there are many reasons to not want a masonry chimney but nothing in the pro column other than aesthetics which is subjective. Is there any advantage? If I bought a house with a masonry stack in great condition that was well built, in great shape, not leaking, had an insulated liner that matched my stove, I would certainly use it.

I personally wouldn’t build a new one or put much money into an old one.
And that is certainly a valid opinion. But if you have a masonry chimney even if it needs some work and a liner it still costs much less to do that than to remove it patch everything in that was effected and then put up a prefab. Even building masonry from scratch really isn't all that much for just a basic stove flue. And how are masonry chimneys obsolete? They are still very common in many areas even for new construction.
 

drussell

New Member
Sep 22, 2020
4
NW Ohio
But if you have a masonry chimney even if it needs some work and a liner it still costs much less to do that than to remove it patch everything in that was effected and then put up a prefab.
In my research, the price for the liner was comparable and actually more expensive than just a new triple-wall chimney setup. That doesn't include removing the masonry chimney, but with the rigid liner, insulation, insulated thimble, and extra stovepipe 90s to make the connection work, it was going to be pushing $1100. For the DuraPlus through-the-roof chimney kit (from TSC), plus chimney and stovepipe, it's about $800-$900.

Thanks for all the feedback. It looks like I wasn't missing something regarding the masonry chimney. I think I'm going to go with the new class A triple-wall chimney. I may end up taking down the masonry chimney to the roofline depending on how things look up there, but for now, I just need to get it up because we're getting down to the wire. I just hope the parts I need to order are still available.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
22,181
central pa
In my research, the price for the liner was comparable and actually more expensive than just a new triple-wall chimney setup. That doesn't include removing the masonry chimney, but with the rigid liner, insulation, insulated thimble, and extra stovepipe 90s to make the connection work, it was going to be pushing $1100. For the DuraPlus through-the-roof chimney kit (from TSC), plus chimney and stovepipe, it's about $800-$900.

Thanks for all the feedback. It looks like I wasn't missing something regarding the masonry chimney. I think I'm going to go with the new class A triple-wall chimney. I may end up taking down the masonry chimney to the roofline depending on how things look up there, but for now, I just need to get it up because we're getting down to the wire. I just hope the parts I need to order are still available.
Do not use duraplus triple wall crap. Double wall insulated is a far better product in every way. It has double the insulation in a smaller outer diameter. It does cost a bit more but it's worth it
 

bcrtops

Feeling the Heat
Nov 14, 2016
285
NW Oregon
Do not use duraplus triple wall crap. Double wall insulated is a far better product in every way. It has double the insulation in a smaller outer diameter. It does cost a bit more but it's worth it
You would be wise to follow this advice. Triple wall is a creosote making nightmare. It just runs too cool.
 

drussell

New Member
Sep 22, 2020
4
NW Ohio
Do not use duraplus triple wall crap. Double wall insulated is a far better product in every way. It has double the insulation in a smaller outer diameter. It does cost a bit more but it's worth it
Good to know. Any recommended brands and retailers? I'm currently looking at DuraTech on NorthlineExpress.com. It's looking like about $1200 for everything above the stove.
 

brenndatomu

Minister of Fire
Aug 21, 2013
5,399
NE Ohio
I've done a couple chimneys using Supervent from Menards with good success...they have their 11% off sale going on too...
 
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