Liner insulation question
- Thread starter frankinri
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You don't have the room for a wrap insulation, you'd need to use a pour down type like Thermix http://www.amazon.com/Chimney-Plus-...1411439362&sr=8-2&keywords=chimney+insulation
I'm not certain on the rigid, but I can say that I had a tough time getting a 6 inch liner down a 7 1/4 square chimney where the tiles were pretty darn straight. 5.5 inch might be the way to go.
How tall is your chimney? Exterior or interior chimney? How's its current condition? Are you sure if it has appropriate gap from combustibles?
pen
I'm not certain on the rigid, but I can say that I had a tough time getting a 6 inch liner down a 7 1/4 square chimney where the tiles were pretty darn straight. 5.5 inch might be the way to go.
How tall is your chimney? Exterior or interior chimney? How's its current condition? Are you sure if it has appropriate gap from combustibles?
pen
Take a standard paint can, 6 1/2" diameter, and lower it with a rope to see if you can get it down the chimney. If you can you have a reasonable shot of insulating it. But remember that the inside of the pipe is six inches, not the outside. For windage sake, figure the pipe to be six and a quarter. Add a 1/2" insulation blanket and you are pretty much out of space to get it down there. But mortar joints and misaligned flue tiles will ruin your whole day.
- Sep 17, 2013
- 85
I thought maybe the existing clay lined chimney could act as the insulation for the steel pipe. Bad plan?
- Sep 17, 2013
- 85
That's a good idea. If I do have to insulate I'm leaning towards the poured in. Any feedback on that product? Or do you think insulation is necessary on this interior chimney?
BruceNorEast
Member
Hi Frank, I believe that the poured in insulation is dry, it's dumped in to fill the empty space.
My understanding is that you may need an insulated liner if your chimney doesn't have the required clearances.
If its a modern home, then you may have them. I would recommend you have it inspected by someone who can verify it.
On my installation, it's an external chimney. I can look up inside and see the one inch gap between the chimney and the combustible wall sheathing (the inside wall, of the room where I am located). If yours is an inside wall the the requirement is two inches. There's also other clearance requirements. Take a look at the following link to get an idea of the external chimney like mine, you'll be able to find one for in internal chimney with a little searching: http://www.rumford.com/code/clearances.html
Good luck!
Bruce.
My understanding is that you may need an insulated liner if your chimney doesn't have the required clearances.
If its a modern home, then you may have them. I would recommend you have it inspected by someone who can verify it.
On my installation, it's an external chimney. I can look up inside and see the one inch gap between the chimney and the combustible wall sheathing (the inside wall, of the room where I am located). If yours is an inside wall the the requirement is two inches. There's also other clearance requirements. Take a look at the following link to get an idea of the external chimney like mine, you'll be able to find one for in internal chimney with a little searching: http://www.rumford.com/code/clearances.html
Good luck!
Bruce.
pour in is not dry it is a dry mix that you mix with water. But to have proper insulation you need 1" or insulation which you will not get. Thia is why we break out liners in situations like this. That being said some insulation is better than none.
BCC_Burner
Feeling the Heat
Check out double wall insulated rigid. But it is only going to fit if the existing liner is straight with no major cement gobs at the joints, which is more common than not.
- Sep 17, 2013
- 85
It's an interior chimney made from cinder block with a clay liner. Does this help? Would pictures be best? Also the rigid says it meets ul without insulation.
- Sep 17, 2013
- 85
- Sep 17, 2013
- 85
That would remove a lot of headaches if I have to insulate. How do you know that stove can use that size. The manual only talks about 6 inch.
- Sep 17, 2013
- 85
It's not perfectly straight and there is globs. I think after I remove the globs I could man handle it down there. I will check out the dimensions on that stuff.
Bruce - I don't understand how you can "see" the 1" clearance requirement by "looking up inside". The clearance is measured from the exterior of the masonry (the side that faces the house) to the EXTERIOR shiething of the house. How can you see this from the inside wall, and how could you see it from the outside without ripping off siding?
BruceNorEast
Member
Hi FireMan,
If you go to the link I supplied above (I'll include it here too), and look at the very first image at the top right, you'll see the one inch clearance that I'm talking about. It's the space between the chimney and the interior wall of the room that i am in, when I look up inside the fireplace I see this gap, with some insulation blocking the gap (presumably to prevent fireplace fire sparks from going up into this area).
http://www.rumford.com/code/clearances.html
I have seen other drawings, on other sites, that show the gap I think you are talking about - for the exterior wall clearance. Apparently this is handled several ways; some have the exterior and interior covering touching the sides of the chimneys bricks, with the stud inside the wall set one inch away from the chimney. Another is to have the stud touching the bricks, but only the corner with no more than a one inch overlap. I've also heard of another where they maintain a clearance of 12 inches from the flue to combustibles. But I am not an authority, just trying to understand the requirements myself, and share what I've found.
As one article points out, a lot of this is BS, because the requirement is unbuildable. Imagine a chimney that maintains a one inch clearance to combustibles, it would have to be free standing, out in the yard, with virtually no connection to the house! Seems to get around this the code adds exceptions, when in reality it ought to be re-written to clearly state exactly what is required, and what the builder must do, based on modern testing. But I'm going off on a tangent here...
BCC_Burner
Feeling the Heat
You can search here for threads where people have done it, and I was in a similar situation with a small, clay lined flue, so my 30 is connected to a 5.5 inch flex liner, wrapped with 1/2 inch insulation. My chimney is on the short side, but other than that, it works just fine as long as it's pretty cold out.
- Sep 17, 2013
- 85
BCC_Burner
Feeling the Heat
It's an exterior stone chimney with a clay liner, then the wrapped, 5.5 inch flex liner inside of that. Then I have a T with a snout that protrudes through the rock connected to single wall stove pipe with 2 45's down into my stove. I am swapping out the single wall for double this weekend for both clearance and performance reasons.
- Sep 17, 2013
- 85
In speaking to Englander the maker of the stove and 2 sellers of liners woodland and Rockford the general consensus is that because it's an interior chimney, clay lined, I should use a flex smooth wall 6 inch without insulation, under 25 feet long for optimal use. I found it surprising that the liner salesmen would not try to sell me the insulating kit or the insulated pipe. What do you guys think about this suggestion?
I can't see how the flue could be cold because it's inside. Maybe when the stove is not in use the top 4-6 feet of the run may be cold where it is in the attic and outside on the roof. There will be a steel metal cap in the top stopping weather from entering the liner and the liner surrounding. Maybe I should just insulate at the top under the cap to keep the cold outside from coming into the void between the ss liner and the clay liner. I'm trying to avoid going smaller than 6 inches.
I can't see how the flue could be cold because it's inside. Maybe when the stove is not in use the top 4-6 feet of the run may be cold where it is in the attic and outside on the roof. There will be a steel metal cap in the top stopping weather from entering the liner and the liner surrounding. Maybe I should just insulate at the top under the cap to keep the cold outside from coming into the void between the ss liner and the clay liner. I'm trying to avoid going smaller than 6 inches.
It is about heat transfer to through the masonry also not just keeping the flue warm
R1001.15 Chimney clearances. Any portion of a masonry chimney located in the interior of the building or within the exterior wall of the building shall have a minimumair space clearance to combustibles of 2 inches (51 mm). Chimneys located entirely outside the exterior walls of the building, including chimneys that pass through the soffit or cornice, shall have a minimum air space clearance of 1 inch (25.4 mm). The air space shall not be filled, except to provide fire blocking in accordance with Section R1001.16.
Exceptions:
1. Masonry chimneys equipped with a chimney lining system listed and labeled for use in chimneys in contact with combustibles in accordance with UL 1777 and installed in accordance with the manufacturers installation instructions are permitted to have combustible material in contact with their exterior surfaces.
If you have those clearances or can find a liner that is listed for zero clearance with out insulation you will be ok without the insulation
R1001.15 Chimney clearances. Any portion of a masonry chimney located in the interior of the building or within the exterior wall of the building shall have a minimumair space clearance to combustibles of 2 inches (51 mm). Chimneys located entirely outside the exterior walls of the building, including chimneys that pass through the soffit or cornice, shall have a minimum air space clearance of 1 inch (25.4 mm). The air space shall not be filled, except to provide fire blocking in accordance with Section R1001.16.
Exceptions:
1. Masonry chimneys equipped with a chimney lining system listed and labeled for use in chimneys in contact with combustibles in accordance with UL 1777 and installed in accordance with the manufacturers installation instructions are permitted to have combustible material in contact with their exterior surfaces.
If you have those clearances or can find a liner that is listed for zero clearance with out insulation you will be ok without the insulation
NHcpa
Minister of Fire
I have the clearances described in 1001.15 for an interior chimney. I have a clay lined 7x7 chimney in good condition. This said, is there any merit in running a 6" uninsulated steel flex? I'm now thinking if not insulated and the chimney and tile is in good shape, what is the advantage of running steel flex?
Still is an advantage. Shape of a circle versus the square helps with flow.
Also, a 7x7 is of course 49sq inches, where the 6 inch round is 28.27, which can mean better draft.
You can always try to run it in the clay we have lots of customers that run through clay liners. There is definitely a performance advantage to lining it even with out insulation. If you have the proper 2" clearance the whole way up then you could just drop the liner and pour thermix you would not have enough insulation to get zero clearance but you dont need it and it would still enhance the performance.
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