insulated liner (needed/not needed)

[udris]

I'm a little perplexed on this issue. I have read numerous posts here and am pretty clear about the stated opinions of most Hearth members (because my chimney is unlined brick and in questionable condition ca.1889, I should insulate the liner). The draft issue is secondary here as the chimney is interior and ~28ft. from hearth to crown with a 8"x8" flue. I have a 6" Homesaver Pro 316ti liner ready to go.

So, here's the rub. I have had 2 certified chimney sweep/inspectors look at my chimney and both said I don't need to insulate.
Their arguments basically were that with modern wood burning appliances the liner will never get that hot, in fact, you should be able to put your hand on that ss flex liner and not get burned. Furthermore, the air space between your 6" liner and your 8" flue is already of significant R-value. They both went on to say that the liner manufacturers are basically trying to sell you something you don't need (essentially in cahoots with the code people (NFPA?) who seem to change the codes all the time and are making the requirements unrealistic for most any chimney in any home).

I realize that most professionals on this site will advocate safety first, and for good reason, as well as liability concerns. I guess what i'm asking is, in a real world scenario, not who's wrong or who's right, but what is reasonable?

If say, I cleaned my flue liner twice a year, what are the chances that a creosote fire could burn through a 316ti stainless liner, continue burning to a point where the brick chimney gets hot enough to transfer that heat to nearby combustibles and set the house on fire? Are most people's overloaded circuit boxes more/less of a hazard?

Thanks for your input on this.

 

[moondoggy]

from what i've learned...
for the sake of $300 for a insulation kit I opted to do it. regardless of what. i'm told its better to be safe then sorry.
i dont want to be standing in my driveway watching my house burn saying to myself... $300. bucks why didnt i just do it.
besides it will draft better ..start easier and your unit should run better if i'm not mistaken

doing mine this weekend cant wait to get my stove in.



also, i learned
hit 'advanced search' above
enter insulate liner
and choose the 'in title' dropdown
you will get other posts about this.

 

[BrotherBart]

Send those sweeps over to my house to get their fingerprints removed. Both of my liners run at upwards of five hundred degrees surface temp on startup and are always over three hundred when the stoves are leveled out and running normally, measured two feet up from the stove collars.

 

[ozarkjeep]

yeah, you need to ignore what those [certified] sweep guys are telling you.

My 25' 6" stainless liner is too hot to touch when the stove is running, granted it gets COOLER with the Cat engaged, but its still 200+ degrees.

if you have an interior chimney, and its tall enough to draft, and its a full masonry chimney, you dont need the insulation in my opinion.

if you have draft problems, its helpful.

install a black off plate at the bottom, and seal the top well, and it will be fine.

 

[udris]

Ok. I'll buy the real world experience of Hearth members with regards to the liner temps.
Thanks OzarkJeep for the measured response. I am planning on making a 26 guage SS block off plate with as much Kaowool stuffed in first as I can reasonably fit. I have also parged the chimney in the attic, re-pointed the brick above the roofline, and am making a ss chimney cap to cover the entire top of the install.

I realize this is a hot button issue and that part of me is playing devil's advocate here, but the "better safe than sorry" response isn't always an informed answer. If I lived like that I would move to the suburbs, never let the kids out of the house and never set foot in an automobile. I guess what i'm looking for here is a safe within reason approach.

 

[ozarkjeep]

Correct,

My thoughts are that if the chimney was safe to burn an open fireplace, then its for sure safe with a stainless liner installed.

seems simple enough.

 

[udris]

OzarkJeep,

I should qualify my initial post. When I said ca. 1889 chimney in questionable condition, I meant that it certainly has all the issues of a chimney that old (soft, crumbling mortar, some missing bricks which I have replaced, etc.). Like I said, I re-pointed above the roof, parged in the attic after replacing missing bricks, etc.. Regardless, I would not burn an open fire in this fireplace or unlined chimney today.

 

[ozarkjeep]

I gotcha Udris,

I was just explaining my simplistic logic.

if a liner can make an otherwise unsafe chimney safe, then it for sure is safe in a workable chimney.

 

[elkimmeg]

you are dealing with a 125 year old chimney brick chimney un lined running there floors surrounded by wood combustibles and you question the need for safety?

125 old mortar joints will be questionable as well as the bricks I doubt you have AS MUCH INTEGRITY IN THAT CHIMNEY YOU ARE BEING LED TO BELIEVE
THAT AGE MORTAR TURNS INTO POWER. Over time normal house movement and settlement can cause brick to crack and mortar joints to crack. You can't see it,
because it is encased in walls. Excuse me but your experts are idiots they have no regard for your own personal safety and display a lack of knowledge. Codes were written to protect people from idiots like them and to protect you your family and your home

1/2" of insulation and the liner will list you current chimney to UL 1777 standards the insulation has a rating to zero clearance to combustibles and is used should any part of an aged chimney not meet safety factors. It restores the saftey and can withstand the 2100 chimney fire temps rating contains the fire within the liner and protects it from spreading to combustibles Another factor mentioned is what do you think 2000 degrees does to old mortar and bricks? Al it needs is one place to find a CRACK OR LEAK and at that temperature instant fire to ulta dry framing members.

I repeat no brick un lined chimney can be used unless brought up to UL 1777 standards. there is no debate to be had.

The decision is up to you, whom to believe, but in my town I wouldn't even issue a permit, unless the application included insulation to UL 1777 standards.
I know I can back everything I have said with actual code. it is quite evident these" experts " need to open the code book occasionally and read it. that is if they have one or ever looked at one. I would have a real hard time hiring someone that just gave me that advice. Would they be named Moe Larry and curly? Sorry its post like this, that make valid info on the forum separate the idiots from the real world

 

[moondoggy]

OzarkJeep,

I should qualify my initial post. When I said ca. 1889 chimney in questionable condition, I meant that it certainly has all the issues of a chimney that old (soft, crumbling mortar, some missing bricks which I have replaced, etc.). Like I said, I re-pointed above the roof, parged in the attic after replacing missing bricks, etc.. Regardless, I would not burn an open fire in this fireplace or unlined chimney today.

“better safe than sorry” response isn’t always an informed answer. If I lived like that I would move to the suburbs, never let the kids out of the house and never set foot in an automobile. I guess what i’m looking for here is a safe within reason approach"

i think was your other comment...which doesnt make much sense.
your kidding right man.
seriously, you wouldnt think it safe for a fire, but your gonna stick a 300-600 degree unwrapped glow stick up there?

its "safer within reason" that your house wont burn down if you overfire.

 

[udris]

Elk,

Thanks for the information. I didn't mean to sound naive or inflammatory, I only wanted to clear up conflicting theories.

I am inclined to err on the side of insulating in this case. Given my scenario, how should I proceed?
I don't think I can get that 6" liner (O.D. 6 3/8") down that 8" x 8" flue with an insulation blanket.

Can I get by with a reduction to a 5" liner and insulation blanket? Given the height (~28') and the fact that it is an interior chimney, will that draft sufficiently? I realize that the manufacturer would never approve this but in this situation, it seems the lesser of 2 evils. Others on this site have reported doing the same I think.

Dutchwest 2500X01 insert with 6" outlet.

thanks

 

[fraxinus]

With apologies for sounding like a broken record, let me say that for a chimney of this age and probable condition a poured liner is a better option. Take a look at www.supaflu.com. There are other poured liner systems, but my experience with Supaflu in an 1870 unlined chimney was completly positive and comparable in cost to a stainless liner.

 

[DriftWood]

TherMix Insulation page 14 and 15 HomeSaver UltraPro installation manual.

10. Insulating HomeSaver UltraPro with TherMix Insulation:
TherMix is a specially formulated, dirt-like consistency chimney fill
insulation and is intended for use when relining masonry chimneys
only. Since 1" of TherMix needs to surround the liner on all sides, the
inside flue dimension needs to be a minimum of 2" larger than the
outer diameter of the liner (which is 3⁄8" larger than I.D.). This means a
6" diameter liner would require a flue opening of 83⁄8"
83⁄8".

(broken link removed to http://www.fireplace-chimneystore.com/f/Insallation_of_Ultra_Pro_Stainless_Liner.pdf)

 

[MALogger]

Elk,

Thanks for the information. I didn't mean to sound naive or inflammatory, I only wanted to clear up conflicting theories.

I am inclined to err on the side of insulating in this case. Given my scenario, how should I proceed?
I don't think I can get that 6" liner (O.D. 6 3/8") down that 8" x 8" flue with an insulation blanket.

Can I get by with a reduction to a 5" liner and insulation blanket? Given the height (~28') and the fact that it is an interior chimney, will that draft sufficiently? I realize that the manufacturer would never approve this but in this situation, it seems the lesser of 2 evils. Others on this site have reported doing the same I think.

Dutchwest 2500X01 insert with 6" outlet.

thanks

It will fit. I have almost the exact situation as you. 8"x8" unlined brick 100 years old. Last year I installed the liner with insulation. You need to make sure there is no mortar or stuff sticking into the flu and it will slide right down.
As for the top, instead of making a stainless top, I got a nice piece of bluestone cut a hole in the middle and mortared it on the chimney. The liner comes with a cap that sits right on top of that nicely.

 

[udris]

MA Logger. Thanks for the success story. I am having a guy come clean the flue first to get all the obstructions swept away. Coming down from the top for the 1st 20-25 ft. doesn't look like it would be that hard (tested by lowering a 6.5" paint can down on a rope), the last 4-6 feet however looks dicey. I tried to get an uninsulated piece of the 6" liner up from the fireplace and am getting it to barely fit through (this is after a session with the angle grinder cutting away pieces of the old damper frame). I'm afraid that if it's that tight, i'm going to be ripping the insulation blanket forcing it through. Perhaps the 5.5" ss liner with blanket will be a safer bet.

 

[iceman]

Elk,

Thanks for the information. I didn't mean to sound naive or inflammatory, I only wanted to clear up conflicting theories.

I am inclined to err on the side of insulating in this case. Given my scenario, how should I proceed?
I don't think I can get that 6" liner (O.D. 6 3/8") down that 8" x 8" flue with an insulation blanket.

Can I get by with a reduction to a 5" liner and insulation blanket? Given the height (~28') and the fact that it is an interior chimney, will that draft sufficiently? I realize that the manufacturer would never approve this but in this situation, it seems the lesser of 2 evils. Others on this site have reported doing the same I think.

Dutchwest 2500X01 insert with 6" outlet.

thanks

DO NOT USE A 5" LINER YOU WILL HAVE ISSUES
use a 5.5 instead most companies ahve np with that as long as you go up at least 20 feet
5 will probably work against your draft for sure

 

[MALogger]

MA Logger. Thanks for the success story. I am having a guy come clean the flue first to get all the obstructions swept away. Coming down from the top for the 1st 20-25 ft. doesn't look like it would be that hard (tested by lowering a 6.5" paint can down on a rope), the last 4-6 feet however looks dicey. I tried to get an uninsulated piece of the 6" liner up from the fireplace and am getting it to barely fit through (this is after a session with the angle grinder cutting away pieces of the old damper frame). I'm afraid that if it's that tight, i'm going to be ripping the insulation blanket forcing it through. Perhaps the 5.5" ss liner with blanket will be a safer bet.

Just don't insulate the last 4-6' but definitely go with the 6". I used the paint can to test and to knock of pices of mortar sticking out.

Craig

 

[theheatelement]

I wouldn't personally insulate a liner and I am a manufacture of liners unless the liner was approved by Intertek or UL with insulation normally that is done with 304 grade SS steel... all of our liners which are 316ti require no insulation and we have had no problems over the last 20 years with this setup.

 

[Jimbob]

The instructions for the Imperial rigid liner I installed in our house in 2001 specifically stated NOT to insulate the liner.
I followed those instructions and haven't had any problems with the liner, although I wonder if insulating it would have kept it cleaner by keeping temps in there higher. I haven't had a huge amount of soot, but even less would be better.

My .02

 

[tbl01]

I " just went thru the same scenario with my new stove this past friday. I went with the 5.5 " liner , fully insulated. i was concerned the 6" would of have some issues with 1" of insualtion.( flue is standard 8 x 12. Inside diameter on the short side was just about 7". 6" with 1" insualtion puts it at 7". Tight.

Anyway the 5.5 inch liner went down the chimney no problem. Went with a blockoff plate as well.

No problems with draft. I Might actually be too much draft. Chimney is about 22' long.

Stove is damped down almost all the way and stove temp is around 500F.

Went with magnflex kit. Very nice product. Will use this kit when we re-do neighbors stove which is vented directly to the existing terra cotta flue.

I woudnt go anysmaller then 5.5". just my two cents.

GM