Insulated Liner?

[jhousek1]

I will start by just throwing the Question out.........Do I need my chimney liner insulated?
Now I will give some information on my install. I installed my Heartstone morgan select (which just about fits in my fireplace) in April of 08. Several of my friends consider themselves "experts" on woodburning and they all told me to just put the pipe into the opening and box of the smokebox. I didn't like this idea because my chimney is probably 80yrs old and it just didn't seem safe to me, but after purchasing the stove i didn't have alot of money. After reading up on the internet, everything I could find, and talking to a Stove dealer I decided to use 25ft of T316 flexpipe. The install had a few problems but was done it in one day. NOW the thought here is .......The air in the chimney keeps getting heated by the pipe and cannot leave the chimney because the top is sealed. The air surrounding the pipe is Actually insulation. Cleaned the chimney 3x last season and found nothing unusual......a little pile in the stove each time. I guess I am wondering is it worth insulating the liner since it will be a major project to do so? Or if it is working well just leave well enough alone? Thank you to all who answer I enjoy reading your feedback.

 

[burntime]

It is much safer, the performance is much better as well. Isn't that the point? I had my stove both ways and I actually had the chimney heat up in the attic and cause ice damning...no problem now that it is insulated.

 

[jhousek1]

Its funny you bring that up, last year i had ice damming for the first time in 10 years, i never thought it was the stove! Thank you

 

[burntime]

It only took me 2 years to figure it out :lol: Actually I got it the first year but was wishfull thinking it would go away...nope, insulation solved it. The stove also operated better with the liner and block off plate. I would not run a stove without it now. I did not believe it until I redid it. The heat output difference and the ability to dampen the stove increased dramatically!

 

[szmaine]

Oh no. We have a center chimney, so we didn't insulate. But we already have an ice dam problem on the north side of the house, it probably will be a glacier this year.
Anybody here ever use the pour in stuff?

 

[johnn]

firestarter38. An 80 year old chimney, maynot be as air tight as the motor joints may reflect. If the foundation has settled any, or it went without a rain cap,or a chimney fire or two and it is leaking air. I prefer to think that the air is robbing heat from the pipe rather than the pipe warming air in your case. Being sealed at the top, i feel refers mainly to shedding water.

 

[johnn]

szmaine:

my sweep i believe called it THERMIX, He mixes his own with so many shovels of sand, to mortor,to vermiculite. I can call him for more specifics if you would like to compare notes,,PM me if you so desire

 

[szmaine]

szmaine:

my sweep i believe called it THERMIX, He mixes his own with so many shovels of sand, to mortor,to vermiculite. I can call him for more specifics if you would like to compare notes,,PM me if you so desire

It's too late to do any thing this year I guess, since the block off plate is mortared into the chimney cap. But yes I would be interested in a DIY insulation recipe.
Why don't you post it here - I bet other folks would be interested.

Does any one think that insulating the exterior of the chimney in the attic would help - maybe bundle it up in some unfaced fiberglass batts? or is that a stupid idea?

 

[sandie]

I just had an install and it was flexitube of some sort and he said he felt that the non insulated was fine although when I looked at it when it was cut it looked insulated to me. The black pipe that goes to the flex pipe from stove is not insulated that I saw but the length of it is about 3 feet to the flex tube. I did a burn last night and it seemed like when I put the kettle on that the steam was going up the chimney not out to the room. Could there be a draft up the chimney? The block off is at the top, I wanted it to be down near the bottom but he felt top was fine. Can I do a bottom block off also? Worried that the chimney is getting the moisture and that the house is NOT. This stove was placed inbetween walls of stone fireplace but not in the fire place itself but just in front of it. Hard to describe out we could stand between the walls and then be at the fireplace which was waist level in about 18" or so. Unusual but so.

 

[Bubbavh]

I just had an install and it was flexitube of some sort and he said he felt that the non insulated was fine although when I looked at it when it was cut it looked insulated to me. The black pipe that goes to the flex pipe from stove is not insulated that I saw but the length of it is about 3 feet to the flex tube. I did a burn last night and it seemed like when I put the kettle on that the steam was going up the chimney not out to the room. Could there be a draft up the chimney? The block off is at the top, I wanted it to be down near the bottom but he felt top was fine. Can I do a bottom block off also? Worried that the chimney is getting the moisture and that the house is NOT. This stove was placed inbetween walls of stone fireplace but not in the fire place itself but just in front of it. Hard to describe out we could stand between the walls and then be at the fireplace which was waist level in about 18" or so. Unusual but so.

A "kind of" easy fix would be to make a lower block off plate and pack the old damper area with rockwool to keep the heat from going up the chimney. Another good idea would be to also pack the top of the chimney (above the roof line) with rockwool. The top plate is usually just siliconed on so easy enough to cut it loose with a razor knife and reseal with some clear silicone.
The whole project should only be about $30.

 

[oconnor]

szmaine:

my sweep i believe called it THERMIX, He mixes his own with so many shovels of sand, to mortor,to vermiculite. I can call him for more specifics if you would like to compare notes,,PM me if you so desire

It's too late to do any thing this year I guess, since the block off plate is mortared into the chimney cap. But yes I would be interested in a DIY insulation recipe.
Why don't you post it here - I bet other folks would be interested.

Does any one think that insulating the exterior of the chimney in the attic would help - maybe bundle it up in some unfaced fiberglass batts? or is that a stupid idea?

Insulating the exterior of the chimney in the attic COULD cause a fire hazard if done wrong. Masonary chimneys require 1 to 2 inches of airspace around them giving clearance to combustibles. That isn't saying that they must be two inches from combustibles, and can be surrounded by non combustibles, but that there must be an airspace, unoccupied, before reaching combustibles.

Lining a chimney with a stainless liner doesn't change this requirement. However, lining it with an insulated liner, depending on the approval of the liner and insulation used, can remove the airspace requirement all together in a chimney renovation situation (Like relining a chimney- new construction will still require an airspace - ULC/CAN 635 refers to existing flues, and ULC/CAN 640 refers to new construction. I believe UL 1777 is similar for US residents)

To insulate the liner, different manufacturers specify different methods. Some require Thermix, some prohibit it and require a ceramic fibre blanket, and some prohibit any insulation at all. It all has to do with how the requested the system be used during thier testing, and is reflected in thier written installation instructions, which are also reviewed as part of the certification process.

In the end, get the instructions that come with your liner system, and follow thier instructions for insulating the liner. Until then, you still need (code requirement) a continuous airspace around the exterior surface of the brick chimney. I believe the requirements are 2 inches around a chimney that is internal to the house, and 1 inch for chimneys on an external wall.

To get it insulated and maintain that space, build a chase and keep all insulation and materials out of the airspace.

 

[johnn]

szmaine:

my sweep i believe called it THERMIX, He mixes his own with so many shovels of sand, to mortor,to vermiculite. I can call him for more specifics if you would like to compare notes,,PM me if you so desire

It's too late to do any thing this year I guess, since the block off plate is mortared into the chimney cap. But yes I would be interested in a DIY insulation recipe.
Why don't you post it here - I bet other folks would be interested.

Does any one think that insulating the exterior of the chimney in the attic would help - maybe bundle it up in some unfaced fiberglass batts? or is that a stupid idea?

szmaine: ~I simply dont have the experience and knowledge of many (great forum, wouldn`t you agree) however for those who can utilize Thermix;,,it does carry additional weight due to the materials used.. Though it is lighter than say mortor or concrete,,a more substantial lower block off plate may need to be installed. My smoke chamber is quiet tall as it reduces down to the flue size and would require many bucketts of mix to be prepared and raised. (unless i can raise the block off plate substantially in heighth and utilize wrap below that point). Your chimney should be inspected and your application discussed with a certified chimney inspector or sweep, possibly both. It will add weight to the whole mass and structural strength should be virified. I`ll give him a call, however he is quite busy as I waited a month for just an inspection. I`ll get back with you

 

[szmaine]

szmaine: ~I simply dont have the experience and knowledge of many (great forum, wouldn`t you agree) however for those who can utilize Thermix;,,it does carry additional weight due to the materials used.. Though it is lighter than say mortor or concrete,,a more substantial lower block off plate may need to be installed. My smoke chamber is quiet tall as it reduces down to the flue size and would require many bucketts of mix to be prepared and raised. (unless i can raise the block off plate substantially in heighth and utilize wrap below that point). Your chimney should be inspected and your application discussed with a certified chimney inspector or sweep, possibly both. It will add weight to the whole mass and structural strength should be virified. I`ll give him a call, however he is quite busy as I waited a month for just an inspection. I`ll get back with you

Thanks, ml - much appreciated!

 

[rhalligan]

I did a lot of research on this after several installers balked at the idea. Long story short - I did my own install - with a flexible liner and insulation. Why not? It isn't that expensive, it improves performance and it is safer. It also got my inspection cleared in about 1 second flat when the inspector saw I had insulated it - he said if it was up to him it would not be an option. Just my 2 cents - but I am glad I did it.

 

[CarbonNeutral]

an insulated liner might result in an overfiring stove which then would require a flue damper which gulland rejected in favor of altering his 2ndary air intake with a moveable plate.& not ul kosher....

Can't understand what you mean here, but insulating your liner is not going to cause an overfire in the stove.

 

[burntime]

He is thinking that the higher efficency is going to increase a problem. I guess if it is already over firing it will but I can not see it creating the problem...I say a block off plate and insulation is a must and to not do it is a waste of efficiency. I have had it both ways and can say with out a doubt that insulated is the way to go!