Chimney Liner Insulation

[fdb16]

So I am replacing my existing wood stove. The current chimney is 20' masonry with clay flue liner 7*10 rectangle. The new stove is 6" round pipe, the old was 8". I posted previously with another question related to the stove and ultimately the advice given was I would be best served installing a 6" SS liner as the current set up is too large and I will have poor drafting. On this I am in agreement as this is the general consensus of all the research I am able to do. I was also advised I would need to insulate the liner. On this I am reading conflicting information. I have read that it is not necessary given the current clay flue tiles in place but would assist in my drafting as it would allow the flue to heat up quicker and at higher temp. My trouble is I would either have to ovalize the liner and then figure out how to unovalize the top or bottom, I would have to go in through the top or the clean out of the chimney, or remove the clay flue tiles. If I go through the top I have to figure out how to unovalize and istall the tee through the cleanout somehow so it would seem pulling up through the clean out would be the better choice in that scenario. Now, thats if I wanted to wrap the liner. What I am also considering is installing the SS liner without insulation for this winter then depending on how it drafts then potentially using pour in insulation next season. My only concern with the pour in insulation is now the clean out would no longer be usable. Seems like I am going to have an issue any way I try to do this. Any thoughts or guidance on this would be appreciated.

 

[begreen]

Duraliner is a complete system for this type of install including the oval to round transitions.
Pour in is not fully effective unless the liner is completely centered all the way down.
Is the chimney flue straight or offset?

 

[fdb16]

Flue is straight shot top to bottom, looking at those duraliners it appears they are in sections. For the cost I am thinking I should just ovalize one myself or just make a clay wrecker and knock em out. I was thinking I could get away with no insulation though because of the clay liner.

 

[begreen]

Flue is straight shot top to bottom, looking at those duraliners it appears they are in sections. For the cost I am thinking I should just ovalize one myself or just make a clay wrecker and knock em out. I was thinking I could get away with no insulation though because of the clay liner.

Yes, they are rigid sections. Each one is pop-riveted to the next with ss pop rivets. It's a good system that works well. Member @Hogwildz has it in his house.
There must be a dozen threads this month alone on why an insulated liner is usually required and the benefits. Please review.

 

[Riteway]

Flue is straight shot top to bottom, looking at those duraliners it appears they are in sections. For the cost I am thinking I should just ovalize one myself or just make a clay wrecker and knock em out. I was thinking I could get away with no insulation though because of the clay liner.

You can rent a tile breaker through Rockford Chimney Supply: https://www.rockfordchimneysupply.com/chimney-tool-rental-information

 

[fdb16]

Yes, they are rigid sections. Each one is pop-riveted to the next with ss pop rivets. It's a good system that works well. Member @Hogwildz has it in his house.
There must be a dozen threads this month alone on why an insulated liner is usually required and the benefits. Please review.

I'll look, but I have yet to find anything with any scientific evidence that states adding insulation significanlty increases draft. All I can find is people stating it does. But does it really or is it that those that installed liners benefited from the smaller flue and therefore better draft regardless of insulation. I can't figure how 1/2 inch of insulation is going to make any real significant difference in flue temperature to necessitate the cost of the insulation wrap when the liner is going to be in a lined chimey with a cap. Just my 2 pennies. I am looking at this as a manufacturing ploy to sell more product. Make a product to increase the cost, get the retailers and installers on board and then it becomes industry standard, but does this really make that much of a difference to justify all the other actions I would need to take when otherwise I could just drop a 6" flex liner in the flue, cap and be done with it.

 

[bholler]

I'll look, but I have yet to find anything with any scientific evidence that states adding insulation significanlty increases draft. All I can find is people stating it does. But does it really or is it that those that installed liners benefited from the smaller flue and therefore better draft regardless of insulation. I can't figure how 1/2 inch of insulation is going to make any real significant difference in flue temperature to necessitate the cost of the insulation wrap when the liner is going to be in a lined chimey with a cap. Just my 2 pennies. I am looking at this as a manufacturing ploy to sell more product. Make a product to increase the cost, get the retailers and installers on board and then it becomes industry standard, but does this really make that much of a difference to justify all the other actions I would need to take when otherwise I could just drop a 6" flex liner in the flue, cap and be done with it.

It makes a huge difference and makes the whole setup much safer. I almost never see a chimney that actually has the required clearances to combustibles. Without them the heat transfer can become dangerous over time. Insulation takes care of that.

But insulation does not increase draft. It makes it easier and faster to establish draft. It maintains draft longer as exhaust temps drop off. It greatly reduces creosote buildup. And it brings chimneys up to code and maintains ul listings for the liner.

 

[begreen]

That 1/2" of kaowool insulation makes the difference between a zero clearance chimney and the current 2" interior chimney clearance requirement, which most chimney's don't have, especially old ones. That is an important safety issue. The insulation keeps the flue gases hotter. This is what both improves the draft and keeps the liner much cleaner. If you want to know the mathematical relation between flue temp and draft strength, here is the formula. Flue temp is T1.



(broken link removed to https://www.gutenberg.org/files/22657/22657-h/chapters/chimneys.html)

 

[fdb16]

It makes a huge difference and makes the whole setup much safer. I almost never see a chimney that actually has the required clearances to combustibles. Without them the heat transfer can become dangerous over time. Insulation takes care of that.

But insulation does not increase draft. It makes it easier and faster to establish draft. It maintains draft longer as exhaust temps drop off. It greatly reduces creosote buildup. And it brings chimneys up to code and maintains ul listings for the liner.

I have the required clearances to combustibles. The stove is in the basement and penetrates through the concrete foundation into a masonry chimney with a clay flue liner. So that is not a problem. Am I reading that the UL listing for a chimney liner is insulation dependent? I don't see how thats possible without it being sold as one product. So what I'm left with is it makes it easier and faster to establish draft and maintains draft longer as exhaust temps drop off. I have heard this but can not find any empirical data showing this to be fact, everything I find is analytical. Is there any data to show exhaust temps with and without insulation? I cant imagine a liner in a clay lined chimney with a sealed cap would have a much larger decrease in exhaust temp with insulation. I am sure it makes a slight difference but is it significant?

 

[brenndatomu]

but I have yet to find anything with any scientific evidence that states adding insulation significanlty increases draft. All I can find is people stating it does.

So what, do you think that everybody on Hearth owns stock in ceramic insulation manufacturers and are on here hawking it just to drive stock prices up?
Higher flue temps mean better draft and a cleaner liner...an insulated SS liner that weighs ~100 lbs is going to steal a whole lot less heat away than several tons of uninsulated masonry...and just a few degrees can make a big difference...try starting a cold stove at 70* outside versus 50*...many (most) chimneys won't allow a cold start at 70...most will at 50...that's only 20* difference...and a minor change in flue temps affects things the same way too.
You are correct that people do benefit from the correct size flue (and round vs square/rectangle too) but I know I have read more than once where a member here pulled out their un-insulated SS liner to insulated it, with a nice performance improvement as a result.

 

[fdb16]

So what, do you think that everybody on Hearth owns stock in ceramic insulation manufacturers and are on here hawking it just to drive stock prices up? [/QUOTE

Yes, that is exactly what I am saying.

Higher flue temps mean better draft and a cleaner liner...an insulated SS liner that weighs ~100 lbs is going to steal a whole lot less heat away than several tons of uninsulated masonry

I am not arguing this fact. I am simply asking the question, will the insulation make that much of a difference? I would assume having a unisulated SS liner would also do this, I am planning on putting in a liner for this and the to decrease the amount of air that need to be displaced.

...and just a few degrees can make a big difference...try starting a cold stove at 70* outside versus 50*...many (most) chimneys won't allow a cold start at 70...most will at 50...that's only 20* difference...and a minor change in flue temps affects things the same way too.

I'm a little confused by this statement. I think you meant to put different numbers in a different order so I won't speculate.

You are correct that people do benefit from the correct size flue (and round vs square/rectangle too) but I know I have read more than once where a member here pulled out their un-insulated SS liner to insulated it, with a nice performance improvement as a result.

I am not arguing that there could be a benefit. What I am asking is does anyone have data that is not analytical to justify the increased cost and added work to put 1/2 inch of insulation on a pipe that is going to be inclosed in a masonry chimney with a clay flue. I am not trying to attack anyones beliefs. I am just asking if there is data somewhere. I cant be the only person that likes to see data and analysis.

 

[bholler]

I have the required clearances to combustibles. The stove is in the basement and penetrates through the concrete foundation into a masonry chimney with a clay flue liner. So that is not a problem. Am I reading that the UL listing for a chimney liner is insulation dependent? I don't see how thats possible without it being sold as one product. So what I'm left with is it makes it easier and faster to establish draft and maintains draft longer as exhaust temps drop off. I have heard this but can not find any empirical data showing this to be fact, everything I find is analytical. Is there any data to show exhaust temps with and without insulation? I cant imagine a liner in a clay lined chimney with a sealed cap would have a much larger decrease in exhaust temp with insulation. I am sure it makes a slight difference but is it significant?

Is the outside of your chimney 1" from any combustible material? If not you don't have the required clearances.

And yes I am saying to my knowledge there are not any liners listed for use with solid fuel without insulation. The reason they are sold separately is because that same liner can be used for liquid fuel without insulation. And there are often multiple insulation options.

You can't just dismiss valid reasons based on code and listing requirements simply because you don't understand them.

My empirical data is years of experience in the field cleaning insulated and uninsulated liners. It works.

 

[fdb16]

Is the outside of your chimney 1" from any combustible material? If not you don't have the required clearances.

And yes I am saying to my knowledge there are not any liners listed for use with solid fuel without insulation. The reason they are sold separately is because that same liner can be used for liquid fuel without insulation. And there are often multiple insulation options.

You can't just dismiss valid reasons based on code and listing requirements simply because you don't understand them.

My empirical data is years of experience in the field cleaning insulated and uninsulated liners. It works.

This doesn't make any sense, if I had my chimney inspected and it passes how do I not have the required clearances? Its a masonry chimney with a clay flue liner that is in tact. The only reason for the new liner would be draft, that is it. I could use the chimney without new liner, the draft would just be terrible.

 

[bholler]

This doesn't make any sense, if I had my chimney inspected and it passes how do I not have the required clearances? Its a masonry chimney with a clay flue liner that is in tact. The only reason for the new liner would be draft, that is it. I could use the chimney without new liner, the draft would just be terrible.

Inspected by who and to what level?

 

[Hogwildz]

You gentlemen offered very sound advise. It appears the OP is not obtaining the answers he was looking for, and therefore will not accept the sage advice given. It does not take a rocket scientist to understand that a warmer pipe drafts better, and accumulates less creosote. The poster can take the very good advice, or ignore and go his own route. No sense spinning wheels here.

 

[fdb16]

I had a level 2 inspection performed a few years back and it passed inspection. As far as advice goes, I appreciate the advice. Is it not acceptable to question these things and have a discussion. I am not trying to put down any ones advice. I am a health and safety professional that works in insurance and part of my occupation is to interpret codes and regulations and typically end up with more questions than answers doing so. I would think there would be more data available to prove that there is significant draft increase. I am not doubting there is draft increase, but is it significant is what I am searching. You're right you don't have to "spin your wheels" here if you don't wan't. I am not looking to ping pong the same statements back and forth or to argue and am certainly willing to accept that there is a significant temp increase and that they are maintained. I am not here to actively argue against that, I am just looking for data to back it up. I apologize if anyone has taken it that way. I thought coming to this forum would get me to that information quicker, as in someone would say, oh yeah they did a bunch of studies at CSIA and this is proven to be fact. That is all. I am planning on adding insulation based on professional opinions in this group but I think its certainly acceptable to question things.

Edit: I am starting to question that inspection now considering the 1 inch clearance from masonry chimney to combustibles. I don't see how that could be possible with chimney up against the exterior of the house unless they found some type of protective barrier. Now im looking for the inspection.

 

[Mech e]

That 1/2" of kaowool insulation makes the difference between a zero clearance chimney and the current 2" interior chimney clearance requirement, which most chimney's don't have, especially old ones. That is an important safety issue. The insulation keeps the flue gases hotter. This is what both improves the draft and keeps the liner much cleaner. If you want to know the mathematical relation between flue temp and draft strength, here is the formula. Flue temp is T1.

View attachment 263974

(broken link removed to https://www.gutenberg.org/files/22657/22657-h/chapters/chimneys.html)

Begreen, that equation is a bit mysterious. If you do a unit analysis, it comes out to pressure = (lbs)/(in x degrees R). Makes no sense. I guess that factor (.52) has units of (degrees R)/(in) to straightens the units out??

 

[Hogwildz]

I had a level 2 inspection performed a few years back and it passed inspection. As far as advice goes, I appreciate the advice. Is it not acceptable to question these things and have a discussion. I am not trying to put down any ones advice. I am a health and safety professional that works in insurance and part of my occupation is to interpret codes and regulations and typically end up with more questions than answers doing so. I would think there would be more data available to prove that there is significant draft increase. I am not doubting there is draft increase, but is it significant is what I am searching. You're right you don't have to "spin your wheels" here if you don't wan't. I am not looking to ping pong the same statements back and forth or to argue and am certainly willing to accept that there is a significant temp increase and that they are maintained. I am not here to actively argue against that, I am just looking for data to back it up. I apologize if anyone has taken it that way. I thought coming to this forum would get me to that information quicker, as in someone would say, oh yeah they did a bunch of studies at CSIA and this is proven to be fact. That is all. I am planning on adding insulation based on professional opinions in this group but I think its certainly acceptable to question things.

Edit: I am starting to question that inspection now considering the 1 inch clearance from masonry chimney to combustibles. I don't see how that could be possible with chimney up against the exterior of the house unless they found some type of protective barrier. Now im looking for the inspection.

You're not going to find a graphs and documented statistics, documented data, etc here. What you get here is real world hands on experiences. We are not a bunch of engineers with highly accurate tools and such. You'll find more trial & error knowledge here, but most general things are tried and true. Liners & insulation being one of those. Even many with interior chimneys that may be within clearances, will insulate to achieve the best draft & safety possible. The warmer you keep the stack, the less cresosote you will have, which is the real plus of a liner, and the better draft you will have. You're getting at minimal 2 benefits here. How many degrees difference, there is no tell all, each system is vastly different. The common thing is all draft better when insulated. It is easiest to insulate the liner prior or while installing the liner. If you want to omit the insualtion, and then find you want or need it, now you have to pull the liner out and reinstall. Not real fun. Sorry to say, but you are overthinking this, wanting a bunch of data in front of you to make a decision, and that is just not going to happen. Your best bet for that is to contact each liner manufacturer, and see if they will share their data with you regarding insulated vs. uninsulated liners. The bucks it costs to insulate are more than worth the cost, considering the advantages. Do yourself a favor and figure on a block off plate also.

 

[fdb16]

Do yourself a favor and figure on a block off plate also.

I decided to bust out the old clay liner, which was in good shape but had to go to fit the insulation. That was fun, is a statement I am sure no one has ever made! Wrapped the pipe and shoved her down. All set up and ready to go now. Not sure what a block off plate is but I assume it has to do with a fireplace. I just have a hearth, no fireplace. It was designed for a woodstove and in the basement so it brick on concrete foundation.

Thanks everyone for the advice.

 

[moresnow]

May as well post a few pics of your install. What stove are you installing?

 

[logfarmer]

I decided to bust out the old clay liner, which was in good shape but had to go to fit the insulation. That was fun, is a statement I am sure no one has ever made! Wrapped the pipe and shoved her down. All set up and ready to go now. Not sure what a block off plate is but I assume it has to do with a fireplace. I just have a hearth, no fireplace. It was designed for a woodstove and in the basement so it brick on concrete foundation.

Thanks everyone for the advice.

How long it take you to bust out liner? My chimney setup is very close to yours except mine is on first floor and not in the basement.

 

[begreen]

fdb16. How does the stove connect to the liner? Is there a wall thimble? If so, there is no need or even opportunity for a block off plate. As always, a picture is worth a 1000 words.

 

[begreen]

Begreen, that equation is a bit mysterious. If you do a unit analysis, it comes out to pressure = (lbs)/(in x degrees R). Makes no sense. I guess that factor (.52) has units of (degrees R)/(in) to straightens the units out??

Sorry for the late reply, I just saw this posting. I knew an engineer would be checking the math. The source is listed below the image of the formula.
(broken link removed to https://www.gutenberg.org/files/22657/22657-h/chapters/chimneys.html)

 

[fdb16]

Old Stove, I planned on disassembling and reassembling as an outdoor fireplace but it may be too far gone.



Warped Baffle, Soap Stone removed


New - England 32-NC
I burned it in outside, hence the blackend blocks.



Hooking into the liner with the tee, getting it lined up.



I needed to get the old clay flue liner out so I created this beast here with what I had laying around. Drilled out the rod to accept the flexible rods for the soot eater, hooked her up and let er rip. I have some video on my sons gopro that I haven't downloaded yet.



Barrel full o' flue liner. Probably took about 2-3 hours with some time spent sitting and waiting for dust to settle and a couple of bolt replacements.



Just need to cap her off and hook up the stove pipe and I'll be ready to roll.

 

[BIGChrisNH]

Old Stove, I planned on disassembling and reassembling as an outdoor fireplace but it may be too far gone.

View attachment 264628

Warped Baffle, Soap Stone removed

View attachment 264629
New - England 32-NC
I burned it in outside, hence the blackend blocks.

View attachment 264631

Hooking into the liner with the tee, getting it lined up.

View attachment 264632

I needed to get the old clay flue liner out so I created this beast here with what I had laying around. Drilled out the rod to accept the flexible rods for the soot eater, hooked her up and let er rip. I have some video on my sons gopro that I haven't downloaded yet.

View attachment 264633View attachment 264634

Barrel full o' flue liner. Probably took about 2-3 hours with some time spent sitting and waiting for dust to settle and a couple of bolt replacements.

View attachment 264635

Just need to cap her off and hook up the stove pipe and I'll be ready to roll.

View attachment 264638

Let me know how you like it. I've got the NC-30 and I love it. I noticed the doghouse that supplies some of the secondary air is gone on the new version that you have, it used to be in the center of the inside of the door frame at the front of the stove. Curious how this new one will burn. On mine, when the stove box is really up to temp and you cut back the primary air, the air coming out of the doghouse would look like a little flamethrower.