Pulled the trigger on a new stove-- time to replace the flexliner? (photos)

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jetsam

Minister of Fire
Dec 12, 2015
5,323
Long Island, NY
youtu.be
Well please check the actual building code before buying anything from him. It doesn't read as he claims.

I didn't say anything about codes, and I don't particularly care what the codes say. I am talking about common sense, safety, and performance.

A clay flue liner in a masonry chimney is perfectly acceptable in PA if done right. No need for a stainless steel liner, and certainly not a more expensive insulated one.

That's great for whatever accountant is in charge of chimney regulations in PA. Physics doesn't care what the rule book says, and your clay liner won't work any better if you make it legal or illegal.

I think that you have conflated two different issues, or at least conflicting engineering challenges. One is keeping the exhaust temp high enough to burn off creosote

That is called a chimney fire, and it is the exact thing that we are trying to avoid. You need to keep all surfaces above 250° to avoid creosote condensation.

the other is keeping as much heat as possible in the house.

Which I accomplish by using a very efficient stove that burns very low. I can only do this because my flue is insulated, otherwise it'd be a creosote factory. I could of course have an uninsulated clay liner, but then I'd triple my wood usage (at least) to heat a giant pile of exterior masonry to 250° and hold it there. That's a deeply unattractive proposition.


If your firewood is for heating your house and not the outdoors, then you want to keep as much heat in your house as safely possible and not send it all up the chimney. That way you burn less wood. Again, I think it's better to upgrade older houses if they have combustibles too close to a chimney than to just send more heat out the chimney and waste wood. That also isn't environmentally friendly as it results in more greenhouse gases being released into the atmosphere.

So if you want to burn less wood and not have regular chimney fires, insulate your flue. It's that simple. No study of local regulations required.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
27,054
central pa
That's great for whatever accountant is in charge of chimney regulations in PA. Physics doesn't care what the rule book says, and your clay liner won't work any better if you make it legal or illegal.
It is the same code nation wide. The code really is about safety which when built correctly and in good condition clay lined chimneys can be perfectly safe. But you are absolutely correct they will never perform as well as one with an insulated stainless liner or an insulated prefab.
 

begreen

Mooderator
Staff member
Nov 18, 2005
91,422
South Puget Sound, WA
The chimney that was put in our house for an oil furnace was installed in 1984. It was 100% to code, built by Wesleyans most likely, and had the requisite 2" clearances all the way up through the roof. All gone now, but it was built well. I'm just sorry that the electrical inspector wasn't as much on the ball during that remodel.
 
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bholler

Chimney sweep
Staff member
Jan 14, 2014
27,054
central pa
The chimney that was put in our house for an oil furnace was installed in 1984. It was 100% to code, built by Wesleyans most likely, and had the requisite 2" clearances all the way up through the roof. All gone now, but it was built well. I'm just sorry that the electrical inspector wasn't as much on the ball during that remodel.
The funny thing about that is the clearance is not required for oil or gas furnaces. Just solid fuel. We see a few with proper clearances but it isn't common.
 

clancey

Minister of Fire
Feb 26, 2021
2,059
Colorado
Yea my chimney for the furnace and coal stove was put in about 1926 and the house owners used pie plate-tin --to plug up the holes and darn near killed me....So i say safety first and worry about money later unless you do not have any then you are in for real problems go to a warming place in your area and get some food in your belly but stay safe instead of just rigging something together that you could never trust..Thanks for reading this but this is how I feel about the situation..clancey
 

CharlieTuna

New Member
Jan 10, 2021
52
PA
That sounds moronic!

The fireplace is circa 1815. The clay tiles were installed in the early 80s I believe and I'd have climb up to double check, but I want say it's 8x12 rectangular.

Well, understand that for thousands of years, a central masonry chimney was extremely desirable to radiate heat to the house. (This is the first place I've ever read people opposing that idea...) So, it shouldn't be surprising that people used the chimney also as a support column. Someone may have used green wood in a construction like that expecting to replace it at a later date, but it didn't happen for whatever reason. It's not at all smart to have kept it that way. Using the chimney as a support column falls under a different section of the code usually than when its part of a masonry wall. The details are scarce because it requires an architect's involvement (from memory) in a new construction. When you start tearing down the walls and ceiling, look out for that. The important safety issue is the distance from the flue liner to any combustibles. If you have 12" or more, I wouldn't worry about it much, but do check your local code in case.

You have a wonderful solid, old-fashioned masonry chimney. It has excellent thermal storage capacity. I think some people here are very jealous of you.
 

begreen

Mooderator
Staff member
Nov 18, 2005
91,422
South Puget Sound, WA
Someone is assuming too much.
 
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CharlieTuna

New Member
Jan 10, 2021
52
PA
Well this thread sure got going while I was gone.

- I thoroughly understand what I'm getting into in regards to moving from a tube stove to a hybrid stove, maintaining a catalyst, lower flue temps for longer, etc (and am excited about it!).

- My brick fireplace column is pretty beefy, but there are certainly combustibles touching the bricks at both the attic floor and the roof line.

- Given the amount of creosote I clean out of my chimney each season, I have felt like my hearth pad and mantel trim clearances were more of a safety hazard than the flex/masonry/brick chimney set up, but I'm a handy DIY homeowner, not a code-aware chimney sweep which is why I was motivated to post my question to begin with. For me, if insulating this particular liner set up was going to give me performance improvements, then I'll likely pull the old liner out and throw in a new one. It's nothing I can't do in a day and this end of the house is going to undergo some extensive remodeling, so with a new stove also in the cards, the new liner is actually pretty trivial in the scope of the whole picture. I've been renting this house and am in the process of buying it from the owners and so these upgrades are on the ASAP timeline now.

- I'm a member of my town's volunteer fire department and for a town of only 1,900 residents, we sure see an awful lot of chimney fires each winter. I've seen some horrific set ups and some very clogged chimneys and am well aware that a new liner and a sweep is a lot cheaper than the damage that a fire and the fire department will do to my house. I like fire safety.

Thanks for all your inputs.

edit for spelling

My best advice is to read the actual local code, use some basic common sense, follow your instincts, and don't get too worried about people who have never actually seen your chimney. Your house and chimney have operated safely for over 100 years, using more masonry than a new construction would. The chimney has been upgraded with a stainless steel liner above what was there originally. Why change it now? Focus on what concerns you first. As a fireman, you have more than a layman's knowledge about what goes wrong. Follow your instincts. Since your house is an older construction, get input from professional people. Don't just rely on online "experts".

I wish you luck with your new stove. You may need it. There was a big cheer when we finally got the old cat stove out of the house. We are thrilled to have a different stove now that can run hotter and burn more polluting creosote.

No, I didn't expect all of this either...
 
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brenndatomu

Minister of Fire
Aug 21, 2013
6,792
NE Ohio
You do realize @CharlieTuna that you have very very slim chances of changing any minds about this particular issue here?
Now, that said, carry on...I think there are many that find it entertaining...
 
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CharlieTuna

New Member
Jan 10, 2021
52
PA
I didn't say anything about codes, and I don't particularly care what the codes say. I am talking about common sense, safety, and performance.

I am talking about common sense too. If the OP's chimney has been safe for over 100 years, why is it a safety hazard now? It's got more masonry around it than yours, I'm sure. It's an interesting thread. Some people are "bible thumping" about the code, which is a bit more complicated than they will admit, if they admit it is the code and not just a "training material". Others don't care about the code...


That's great for whatever accountant is in charge of chimney regulations in PA. Physics doesn't care what the rule book says, and your clay liner won't work any better if you make it legal or illegal.

IMHO opinion, the quest for a universal, "federalized" code comes from large corporate developers, those people who mass produce homes with green lumber and pre-fab chimneys. It's not written for people like the OP who have a much older house, built to older standards and customs. Such people can't go to their local municipal government and have the code clarified for their houses with such a code. The state legislature is too busy to care about them, and they don't contribute enough money either.


That is called a chimney fire, and it is the exact thing that we are trying to avoid. You need to keep all surfaces above 250° to avoid creosote condensation.

Or burn with a secondary system to reduce the creosote, and keep the heat in the house...
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
27,054
central pa
Well, understand that for thousands of years, a central masonry chimney was extremely desirable to radiate heat to the house. (This is the first place I've ever read people opposing that idea...) So, it shouldn't be surprising that people used the chimney also as a support column. Someone may have used green wood in a construction like that expecting to replace it at a later date, but it didn't happen for whatever reason. It's not at all smart to have kept it that way. Using the chimney as a support column falls under a different section of the code usually than when its part of a masonry wall. The details are scarce because it requires an architect's involvement (from memory) in a new construction. When you start tearing down the walls and ceiling, look out for that. The important safety issue is the distance from the flue liner to any combustibles. If you have 12" or more, I wouldn't worry about it much, but do check your local code in case.

You have a wonderful solid, old-fashioned masonry chimney. It has excellent thermal storage capacity. I think some people here are very jealous of you.
You are correct while heating with open fireplaces and early very inefficient woodstoves you did want a central chimney because you were sending a large portion of the potential heat up the chimney with no way to control that. But things have changed allot. We can now control the exhaust gas temp pretty well. We have it to a point where if run properly there isn't much heat left in that exhaust to loose.

You obviously didn't read the provided code. A chimney cannot be used to support combustible structure without a ul-1777 liner rated for zero clearance to the masonry or if it is part of a masonry wall and that combustible is atleast 12" from the clay liner. Which at that point it is being supported by the masonry wall.

You seem to have lots of opinions but very little knowledge of the issues at hand. Btw this is what I am working on today. It was a structure fire caused by lack of clearance to combustibles. I do this stuff all day every day. I don't know what makes you think you are more qualified than me.
 

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bholler

Chimney sweep
Staff member
Jan 14, 2014
27,054
central pa
Or burn with a secondary system to reduce the creosote, and keep the heat in the house...
Wrong it doesn't matter what system you are running the exhaust has to stay above the condensation point to avoid large amounts of creosote buildup.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
27,054
central pa
If the OP's chimney has been safe for over 100 years, why is it a safety hazard now
Old houses catch fire all the time from chimneys that have been that way for 100 years. Everything is fine untill it isn't that is no argument.

The house I am working on now was fine for 40 years then it wasn't.
 
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jetsam

Minister of Fire
Dec 12, 2015
5,323
Long Island, NY
youtu.be
Or burn with a secondary system to reduce the creosote, and keep the heat in the house...

Please don't mistake this for an ad hominum response, but I would expect most persons who have burned one season with a modern stove to know from experience that secondary combustion doesn't excuse you from having a proper install and burning practices. In fact, it often makes them more important because very low burn rates become possible with cat stoves.

Barring a large jump in either catalyst technology or wood stove complexity and pricing, you're always going to have VOCs in the exhaust, and they're always going to condense when they hit a surface that's below 250°.

(And as a side note, if your legislature improperly funds whatever functionaries write local code- creosote works exactly the same way. Creosote condensation doesn't read. It would make just as much sense to argue that there was a coded message about creosote condensation on page 404 of "Gone With The Wind" as to argue that you should vent your stove however is convenient because local codes do or don't allow it.)

Do local codes allow me to install an unvented firepit in my bedroom? Don't know, don't care- it's a bad idea. Would it work differently if only more people studied the codes and there were better laws and more funding and outreach programs to teach people about the codes? Nope! CO poisoning doesn't care about the codes either. Still a bad idea.
 
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bholler

Chimney sweep
Staff member
Jan 14, 2014
27,054
central pa
IMHO opinion, the quest for a universal, "federalized" code comes from large corporate developers, those people who mass produce homes with green lumber and pre-fab chimneys. It's not written for people like the OP who have a much older house, built to older standards and customs. Such people can't go to their local municipal government and have the code clarified for their houses with such a code. The state legislature is too busy to care about them, and they don't contribute enough money either.
If the codes are written only for modern high production construction using prefab chimneys why is there a section on masonry chimney construction? Why are there sections explaining how codes are applied to remodels? What makes you think you can't go to your local code office to have them clarify how codes apply to your old home? You can absolutely do that and many people do.

You are missing the point that most of these codes were written to address issues that came up with previous construction practices. Do I agree with all of them? No absolutely not but that doesn't change the fact that I am required to follow all of them.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
27,054
central pa
best advice is to read the actual local code, use some basic common sense, follow your instincts, and don't get too worried about people who have never actually seen your chimney.
But the advice from someone who didn't even know the difference between an insulated liner and a prefab chimney at the start of this thread who also has never seen their chimney either is more valuable than that from an experienced professional???
 

begreen

Mooderator
Staff member
Nov 18, 2005
91,422
South Puget Sound, WA
This massive diversion is not helping the OP. Time to get a room guys.

beatign_dead_horse.gif
 
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CharlieTuna

New Member
Jan 10, 2021
52
PA
You do realize @CharlieTuna that you have very very slim chances of changing any minds about this particular issue here?
Now, that said, carry on...I think there are many that find it entertaining...

Well, I was just giving the OP my opinion. In life we get what we pay for. If it's important, consult a professional and pay for his opinion. If that central chimney is used as a support column, the lintels connecting to it are usually going to be in a different section of the code. The proper professional to consult about that issue would be an architect or a structural engineer.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
27,054
central pa
Well, I was just giving the OP my opinion. In life we get what we pay for. If it's important, consult a professional and pay for his opinion. If that central chimney is used as a support column, the lintels connecting to it are usually going to be in a different section of the code. The proper professional to consult about that issue would be an architect or a structural engineer.
If you want to continue this discussion please start your own thread.
 
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