# Insulated vs uninsulated chimney liner - tell us about yours”



## elkimmeg (Aug 3, 2006)

He requested a separate post to discuss the topic. So he does not get the wrong idea, I support his efforts to line the chimney.
 We had pros and cons of different materials used in prior post. Like all of us, he trying to workout a cost effective solution.
 He claims I hammered my suggestions from the past post.  To me, I am not trying to be his enemy.

My stand is to do it right, code compliant  using  liner manufactured specs and testing. Its listing requires innsulation to meet ul standards. 

 Let the discussion begin
















https://www.hearth.com/econtent/index.php/forums/viewthread/2634/


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## zzr7ky (Aug 3, 2006)

Hi - 

I'm getting ready to install a SS liner into a 10x10" flue tile.  It will be insulated because the run is only 16' I need all the draft I can get.   As an engineer I can appreciate the slower temp cycling on the masonary components should keep them in better shape longer.

I do understand the cost issue.  My chimney is on an exterior wall also.

ATB, 
Mike


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## precaud (Aug 3, 2006)

Thanks for getting things started, Elk. I would have titled the thread a little differently to get the broadest range of input, but this will do.

According to the specs, the main purpose of putting insulation on stainless liner pipe is to enable the pipe to withstand the 2100F temperatures that might occur in the event of a chimney fire. As an inspector, you understandably want to see every chimney built to withstand that, to take the operator out of the equation.

My stand is that chimney safety is largely in the hands of the operator, and that with intelligent stove operation and regular maintenance, the chance of a chimney fire can be reduced to near zero.

The Chimney Safety Institute of America publishes reccomendations which essentially support my position:

*WAYS TO KEEP THE FIRE YOU WANT...  from Starting One You Don't! 

 Chimney fires don't have to happen. Here are some ways to avoid them : 

: Use seasoned woods only (dryness is more important than hard wood versus soft wood considerations)

: Build smaller, hotter fires that bum more completely and produce less smoke 

: Never burn cardboard boxes, wrapping paper, trash or Christmas trees; these can spark a chimneyfire 

: Install stovepipe thermometers to help monitor flue temperatures where wood stoves are in use, so you can adjust burning practices as needed 

: Have the chimney inspected and cleaned on a regular basis. Clean chimneys don't catch fire!*

(The underlining on that last line is mine, because it gets to the heart of the matter more than anything else.)

My burning habits reflects these recommendations to a tee (pun intended!)

So, I'd like to hear from everyone who has a lined masonry chimney (that's the context here).
Is it a solid or flex liner?
Does it perform well?
Is it insulated, to meet the HT-class code?
What are your maintenance habits?


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## Eric Johnson (Aug 3, 2006)

My previous house had an insulated, flexible liner inside an indoor, brick (no clay liner) chimney. I had a boiler.

It worked great.

Because it was easy to do from the basement, I got into the habit of cleaning it once a week (every Sunday) whether it needed it or not. My theory was that I could sleep easier at night knowing that there would never be enough creosote accumulation in a week's time to torch off a significant chimney fire. 

Sometimes I pulled lots of creosote out during a cleaning (say a gallon out of the 30-foot, 7-inch liner), and sometimes I got just a handful. No rhyme or reason that I could ever figure out about why sometimes I got a lot and sometimes almost none.

I'm sure you'll keep your chimney clean, precaud, but what about the next guy?

BTW, you'll probably get more creosote and less draft if you don't use insulation, for obvious reasons.


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## elkimmeg (Aug 3, 2006)

There is a little more going here than presented.. First of all not all liners need insulation 
 Precaud I can edit the post topic to any way you want

 edited


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## webbie (Aug 3, 2006)

precaud said:
			
		

> Thanks for getting things started, Elk. I would have titled the thread a little differently to get the broadest range of input, but this will do.
> 
> According to the specs, the main purpose of putting insulation on stainless liner pipe is to enable the pipe to withstand the 2100F temperatures that might occur in the event of a chimney fire. As an inspector, you understandably want to see every chimney built to withstand that, to take the operator out of the equation.



My limited knowledge of materials would tell me that an insulated liner would do WORSE at withstanding high temperatures because the heat is kept in rather than radiated out!

I agree this is somewhat of a grey area and pointing to code and instructions/listings does not address all the issues. 

My understanding is that the insulation is there for this reason: If you were to line a very defective chimney without a liner, such as single brick that was deteriorating, the insulation would make certain that the heat transfer did not affect wood that was very close by.

In other words, I am guessing that performance of the chimney was not the intention of insulation, but rather the safety when used in defective chimneys. It makes sense that UL would test chimney lining in UNLINED chimneys.

If true, this does allow for many interpretations when a lining is used in a LINED, INTERIOR or PROPERLY SIZED masonry chimney....which many are! There are situations where insulation also will not fit.

Then there are climate differences.

So, in truth there is no simple answer to this question. In the 1980's, a masonry chimney was up to code. In the 1990's a liner without insulation was fine....in fact, overkill in many cases. In 2020 the codes will probably call for solid titanium along with space shuttle tiles. Or, perhaps woodstoves will burn so clean and put out less heat, so they might be direct vented with plastic!


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## skypager (Aug 3, 2006)

Ok.. I'm trying to fully understand this.  Pardon my ignorance but I don't personaly deal with many solid fuel relines these days.

Is this a correct interpretation?  This is how it sounds to me.

In general:

It is ok to install a un-wrapped liner in a masonary chimney that meets the provisions of NFPA 211.  But.. most chimnies do not meet the standards listed in said code and that is when the safety wrap is required.  Also, If there is no clay flue liner the safety wrap must be used (as the chimney would then not meet  NFPA 211).  It is reccomended that all chimney liners be wrapped because it is difficult if not impossible to insure that the chimney meets NFPA 211 (unless you built it yourself or have documention stating such).

-and-

UL 1777 meets the standards to keep a home safe in the case of a chimney fire.  But it sounds to me that the reason a heat-fab liner must meet that listing with the wrap is so it can be used in the case were a chimney does not meat NFPA 211.

This is what I see in the quotes and documents posted in the other thread.  

For example, this line from the Alternative Energy Retailer link- 

"A liner which carries the full UL 1777 listing can be installed to Zero Clearance within the chimney without insulation so long as the masonry chimney it's installed into meets NFPA 211. Again, if the masonry chimney does not meet the NFPA 211 standard, insulation is required. "

So... I read it that if precaud's chimney meets NFPA 211 and he can prove this, he does not need insulation wrap.

Edit- I also don't see in Heat-Fabs instructions that say the wrap MUST be used in all cases.


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## webbie (Aug 3, 2006)

elkimmeg said:
			
		

> First of all not all liners need insulation to meet the UL 1477 standard. Only the cheaper ones made of 304 ss  require the insulation to   achieve the standard. Ht 2100 ss 316ti  meets the standard, (without insulation) but it is a better grade more durable steel and cost more. This fact has been pointed out here many times before



Can I see the example of this? Perhaps I'm not up to date, but I thought insulation was to protect the surfaces nearby from heat, not to do with the liner temperature, etc. - if this is the case, there is no material composition difference that would affect the need or lack of for insulation.


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## webbie (Aug 3, 2006)

josh said:
			
		

> Ok.. I'm trying to fully understand this.  Pardon my ignorance but I don't personaly deal with many solid fuel relines these days.
> 
> Is this a correct interpretation?  This is how it sounds to me.
> 
> ...



I think this is the case - what I was trying to get at - the insulation is to protect clearances from combustibles next to the chimney. Stainless grade does not make the difference, but rather the condition and clearances of the existing chimney.


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## elkimmeg (Aug 3, 2006)

For simplicity Craig HearthHand book Page 44 and 45

W3.8.3 Cchimney Liners
 There are two standards ul 1777 and a higher standard  HT 2100



 The Ht 2100 does not have to be listed for UL 1777 that listing is the same as  UL 103 HT which is a higher listing

 In retail SS 304 with insulation will meet UL 1777   SS 316ti meets UL 103 HT without insulation.

 you are correct  the insulation has a dual purpose added protection against burnout and keeping the heat in to promote draft

 The point here is the grade characteristics questioned 304 VS 316ti


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## webbie (Aug 3, 2006)

elkimmeg said:
			
		

> For simplicity Craig HearthHand book Page 44 and 45
> The Ht 2100 does not have to be listed for UL 1777 that listing is the same as  UL 103 HT which is a higher listing
> 
> In retail SS 304 with insulation will meet UL 1777   SS 316ti meets UL 103 HT without insulation.



Elk, I don't have the Hearth Handbooks (maybe I should) - but I know the people who wrote them, and they are also on the committee that writes the National Code - perhaps I can check with them.

I still think this specific information is wrong! All these numbers and codes might be easy for you to understand, but they completely confuse me. 

316 or 316Ti are usually specified when burning coal or oil, but 304 is plenty good for wood. I would like to see a particular manufacturers listing or manual which states that their 316 is approved without insulation, but that their 304 is not.

As an example, here is a page where you can download a manual for a Chimalator manual:
http://www.dalsinmfg.com/links/chimalator.html

Quotes from this manual for UL approved liner:

CHIM-A-LATOR® stainless steel liner systems are available in 5" to 12" round diameters. The liner is type 304 or type 316 stainless steel.

Coal burning appliances must be connected only with type 316 connectors and liners.

The CHIM-A-LATOR® liner system is intended for use in an unlined chimney with at least 4" of masonry all around. It may also be used in a properly built masonry chimney with cracked clay tile liners. Another use for the CHIM-A-LATOR® liner is to provide a properly-sized flue for a wood burning appliance installed into a masonry chimney which other wise meets existing codes.

CHOOSING THE CORRECT TYPE OF STAINLESS:

Type 304 (or 304L) stainless can be used for wood, oil and low efficiency gas appliances. Type 304 can also be used as a fireplace liner. The high efficiency gas furnaces require another type of venting system. Refer to the manufacturer's installation instructions before connecting a liner to a gas appliance.

Type 316 (or 316L) stainless should be used for a coal-burning appliance. Type 316 may also be used in any instance noted above where type 304 is specified.
-------------------------end quotes from manual-----------------

There is no instance in this manual where it mentions insulation for either the 304 or 316.

I think Chimneysweep has it about right. The average consumer, dealer or even code official is not able to make sense of all the various numbers and EVERY installation and stove manual (which are often VERY different). 

So we have to distill this information and keep it as simple as possible.

That is, in my opinion - and in order of occurence in the field:

1. Installing liner into an existing lined chimney of good condition for wood burning 
Insulation not required - any grade of stainless that is designed for this job is OK

2. Installing liner into a defective or unlined chimney
Insulation required with ANY stainless grade

3. Installing liner for use with oil or coal
316 alloys will last much longer and are best for this application.

Performance is a separate issue - just as we know an external masonry 8x8 is not ideal, an uninsulated liner in an exterior chimney in Vermont may also cause problems. However, UL listing is for safety....they do not test products for consumer satisfaction.

That is my current opinion and I am sticking with it....for now.


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## webbie (Aug 3, 2006)

From the man who wrote the book:


Q. would the alloy of the stainless make a difference?

A. I don't think the type of stainless has any significant or direct bearing on the need for insulation; I think, but again have not looked at this issue for some time, that the alloy is a consideration of factors like corrosion (and therefore fuel choice) and durability. In any case, the question is moot: just refer to the installation instructions for the listed liner.
---------------------------------------------------

Interestingly enough, we will NEVER accurately answer this question because - insulation would not be required if the chimney was compliant - BUT, as anyone will tell you, almost no chimneys are compliant....even chimneys built recently and inspected by the proper offficials! So, is the customer supposed to assume that their inspected and insured newer house was not done correctly? 

The question of the ages.....

A lot of people are going to throw the responsibility to the liner or the stove manufacturer/manual ...but, keep in mind - the manufacturer probably only tested one way - in a defective chimney with insulation. Again, this has no bearing on a chimney that is compliant.

As Elk knows, there is no subsitute for experience and in-the-field calls.


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## Todd (Aug 3, 2006)

precaud said:
			
		

> So, I'd like to hear from everyone who has a lined masonry chimney (that's the context here).
> Is it a solid or flex liner?
> Does it perform well?
> Is it insulated, to meet the HT-class code?
> What are your maintenance habits?



I have 20' flex 5.5" 316 s/s liner, outside wall masonary chimney, and I insulated the top couple feet under the cap thinking the warm air space inbetween would help. Draft pulls like a champ. Big difference from unlined. I would of used a full insulation wrap if I didn't have the clay liner in chimney or if it was in bad shape. Otherwise I think its a waste of money. If your chimney is in descent shape first try in without the insulation and see how she burns. As far as maintenance, I burned 3 cords last year, sweep it 2 times. Very little soot, maybe a little over a quart.


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## precaud (Aug 3, 2006)

Well this thread has taken some interesting directions, in part because I misdescribed the purpose of the insulation as protecting the "pipe" when it should be protecting the "chimney". Sorry about that. It's a big difference. It looks like posts by josh and Craig have sorted that one out, if to an indeterminate conclusion...



> Precaud I can edit the post topic to any way you want


Thanks Elk, since the purpose here is to get input from lots of members, something like "Insulated vs uninsulated chimney liner - tell us about yours" might be more appropriate.

I'm looking forward to seeing more members post with descriptions of their liner.


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## elkimmeg (Aug 4, 2006)

This is a great education process as precuad wanted pro's and con's good discussion 

edited


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## precaud (Aug 4, 2006)

Elk. for an inspector, you sure rely alot on emotional factors to make your case. I'm not looking for approval from you, or a battle with you, or to prove or disprove code (which, we have now learned is somewhat ambiguous). My purpose was stated clearly from the beginning, and you're doing your level best to put a stop to it. Why not you be silent and let me hear from others, which is what I wanted? Or, better yet, please participate and tell us about your liner, if it fits the criteria. Here again is what I'm asking for in this thread:

I’d like to hear from everyone who has a lined masonry chimney (that’s the context here).
Is it a solid or flex liner?
Does it perform well?
Is it insulated, to meet the HT-class code?
What are your maintenance habits?


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## hearthtools (Aug 4, 2006)

Ok
Im going to post a snip from the other tread just so others that did not read it know how this started.
<snip from other thread>


    Did you get the isulated Saf-T Wrap to go with it?

Nope.

Are you venting a wood appliance into a masonary chemney?
if so then it is required to Insulate the liner.
http://www.heat-fab.com/resources/pdf/PI-LINER.pdf

<snip from Above link>
Saf-T Liner is a high quality U.L. tested and Listed stainless steel lining system designed for relining existing
masonry chimneys. It satisfies code requirements as a substitute for 5/8” fireclay liners and has undergone
extensive testing to make it the leader in the stainless steel chimney lining industry. Heat-Fab recommends that
the installation of Saf-T Liner be performed by an experienced professional who works with chimney and
woodstove related products on a regular basis. Saf-T Wrap is a safe, high quality, easy to install ceramic
insulation jacket for stainless steel lined masonry chimneys. Saf-T Wrap when used in conjunction with Saf-
T Liner will upgrade a chimney to an HT type chimney system. The following instructions are intended as a guide
to assist a qualified professional installer. Check your local building codes and contact local building or fire
officials to obtain any required permits. Warning: Incorporation of parts or materials not manufactured or
supplied by Heat-Fab may not provide a Listed system. Order Heat-Fab’s installation videotape for further
information, available in VHS format.
</end of snip> 

For the Liner system to be listed to the UL 1777 , NFPA 211 is must be wraped.

Here is a story about to wrap or not to wrap.
http://www.aer-online.com/aer/ar-vent1.phtml


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## elkimmeg (Aug 4, 2006)

My liners are 8/8 clay masonry,  Which I built using refractory cement for joint connections.Each stove is in a separate 8/8 flue
 Both stoves are listed to be installed in an 8/8 masonry flue.  The interior of the common 8/8 clay flue is app 47" which is not  3 or even 2 times the cross-sectional code. Both stoves draft as they should.  Pictures of both installations have been posted here on hearth .com As requested I am bowing out of further participation  of this thread. I said nothing Rod,, Hearth tools, had already pointed out
 compliance with the listing.


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## hearthtools (Aug 4, 2006)

I don’t understand Elks comments that the Heatfab is a cheap liner.
316 is only needed for Coal or corrosive type gases.
Wood gases only need to be 304

<snip from Heatfab site>
Saf-T Liner Product Description

Heat-fab Saf-T Liner systems consist of a Stainless Steel Liner Section (fabricated using either 304L or 316L stainless steel) insulated with Heat-fab Saf-T Wrap chimney insulation. The Saf-T Liner systems have been Tested and Listed by Underwriter Laboratories, Inc. to UL 1777 for use in conjunction with any Listed residential appliance (When installed per the manufacturers Installation and Maintenance Instructions). The 304L system is best suited for wood burning applications, whereas type 316L system is equally suited for wood-, coal- or oil-fired installations.

Saf-T Liner is suited for use with solid fuel and older oil- or gas-fired equipment that does not produce condensation in the vent. (For condensing or positive pressure gas appliances we recommend Heat-fab Saf-T Vent or Saf-T Vent CI special gas Venting Systems).

Ideal for relining chimneys that have deteriorated lining, oversized lining, or for lining chimneys with no existing lining, Heat-fab's Saf-T Liner System adds years to the life of a chimney. The product's resistance-welded, 24-gauge stainless steel fabrication meets code requirements and provides optimum safety. As a substitute for 5/8" fireclay liner, Saf-T Liner cannot be beat.

Saf-T Liner is Tested and Listed by Underwriters Laboratories for use with Listed fuel burning equipment that produce continuous flue gas temperatures not above 1000°F when properly insulated with Saf-T Wrap Chimney Liner Insulation.
</end of snip>

Can you give us some brands a *Single wall ridged liner* that is NFPA211 or 1477 UL listed with out a wrap?

I like using the single wall pipe with the wrap (heatfab)over the double wall liners (duraliner) because they are lighter to install, More types of connectors and fittings available and can be used with the more flexable 316 flex liners. The Double wall stuff you have to use their 5 foot double wall flex pipe and you only get a few inches of movement out of them.


The type of SS or gage means nothing to me. I just follow the install instructions.

I do think that having an extra wall or insulation will help draft and keep away hot and cold spots down in the liner that can cause 2nd and 3rd stage creosote buildup.
Where the liner with out insulation lays against the clay or brick. it will also protect the pipe from any acids left behind on the sides of the old chimney.

Btw 
I buy the heatfab in 4 foot lengths with the wrap already installed on the pipe.
Same rating as the double wall liner with less weight more components available and a little less cost.


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## elkimmeg (Aug 4, 2006)

Every installation with liners I read the listing specs.  BMD requires insulation in exterior  walled chimneys but optional for interior chimneys.  316ti multi fuel liners are not required to be insulated 323 ss liners have no insulation option listed Can you state a case where 304 ss can be installed without insulation? This post is as educational to me as it is to all other readers.


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## hearthtools (Aug 4, 2006)

elkimmeg said:
			
		

> Rod can you help me It seems the 2006 international Mechanical codes,  there is no language concerning insulation requirements of liners.. NFPA 211 2006 I still can not find any code language requiring insulation for liners. I need help if it is in code then please point me in the right direction and reference National code. I can't find it. Eventhough I have all 2006 codes  on my computer with Acrobat search/find capabilities What am I missing if I am wrong.
> Every installation with liners I read the listing specs.  BMD requires insulation in exterior  walled chimneys but optional for interior chimneys.  316ti multi fuel liners are not required to be insulated 323 ss liners have no insulation option listed Can you state a case where 304 ss can be installed without insulation? This post is as educational to me as it is to all other readers.  Can you also point out where I can ignore the manufacture's listing requiring a liner insulation? If this is true can, you guide me as to which manufacture's specs are enforceable and the one's that are not, And please base you case on reconised facts. It is possible I've been wrong the past 11 years enforcing  written code. and in one post it can be simplified?



Sorry Elk I have no Data on the code there for I will go by manufacures Specs.
Im with you I just follow the specs for the liner used. 

If I use Copperfields 316I ultra Pro flexable liner and I will have no idea if the masonry chimney has at least 1" of clearance (or cracked tiles) and it says to wrap it with 1/2" foil faced wrap and armor mesh then I wrap it with 1/2" foil face wrap and armor mesh.

<snip from Copperfields 316I ultra pro flex liner instructions>
3. INSULATING THE LINER
Insulation is *required* when venting solid fuel appliances but is optional for wood pellet
appliances, oil appliances, and Category I LP or natural gas-burning appliances.

*Wood And Coal Applications*
There are three scenarios you may encounter when lining for wood and
coal that will affect your choice of insulation options.

In a case where a masonry chimney is found to have at least 1" clearance
to combustibles the minimum insulation requirements are one wrap of 1⁄4"
foil-face insulation or 1" of HomeSaver InsulationMix or TherMix insulation.

When less than 1" clearance exists between the exterior of the masonry and
the surrounding combustibles, *the minimum insulation requirements *are
one wrap of 1⁄2" foil-face insulation, two wraps of 1⁄4" foil-face insulation, or
1" of HomeSaver InsulationMix or TherMix insulation.

The insulation requirement for a properly installed factory-built chimney is one wrap of 1⁄2" foil-face insulation.
</end of copperfield snip> http://www.copperfield.com/Content/installation_pdfs/INSTALL BOOK HS ULTRAPRO.pdf


From the spec sheet of Heat fab
<snip>The Saf-T Liner factory-built Chimney Liner system is Tested and Listed by Underwriters Laboratories for use with Listed fuel-burning equipment that produces continuous flue-gas temperatures not above 1000°F *when properly insulated with Saf-T Wrap chimney liner insulation.* The system is to be installed per manufacturers' instructions.</end of snip>

SO I WANT THE LINER TO BE UL LISTED
In Heat fab Safe T liner the intructions say to use their Safe T wrap Then I use it with the safe T wrap. 

I guess there is an argument that if you dont need/care to have a UL listed Liner system then you dont need to wrap it.

BUT I  WILL NOT INSTALL A LINER that is UNLISTED or not up to manufacures specs.


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## elkimmeg (Aug 4, 2006)

> BUT I WILL NOT INSTALL A LINER that is UNLISTED or not up to manufacures specs.



 I second that, I will not sign off on a liner that does not meet the UL listing  or not installed properly. Which means
 insulation is speced than insulation has to installed

 I too have Sotty Bob catalogue


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## jabush (Aug 4, 2006)

precaud said:
			
		

> I’d like to hear from everyone who has a lined masonry chimney (that’s the context here).
> Is it a solid or flex liner?
> Does it perform well?
> Is it insulated, to meet the HT-class code?
> What are your maintenance habits?



I have an exterior masonry chimney (16 feet) with 6" SS flex liner.  Although the clay tiles were in good shape the sweeps recommended I have it lined and insulated.  Prior to liner and insulation it was hit and miss getting the draft going.  Often times I would have to go out and light some paper in the cleanout door to warm up the chimney, then run back inside and touch off my kindling.  Not fun...
Anywoo, now the system drafts like a champ, no problem at all when the stove is cold.
I haven't cleaned it yet as the install was performed toward the end of last years heating season.  I'll post back on that.
Also, insulation is not a wrap.  They mixed it up in buckets like concrete and poured it down around the liner.


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