Liner insulation question

[NHcpa]

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.

Good answer - thank you! I'm looking to improve draft and I get a bonus "T" for easier cleanout. I would insulate as others have advised, but that would mean knocking out tile and I'm not up for that, although it appears to be an accepted solution.

 

[NHcpa]

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.

Thank you too bholler. I will inquire on the thermix. If I should want to change out the flex down the road, what difficulty if any does thermix pose?

 

[bholler]

Not to much the liner pulls fairly easily and a rotary cleaner gets almost all the thermix out. Thermix is a brand name there are lots of premix pour in insulation out there

 

[frankinri]

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

I have the exception, clay lined. This means I am ok with just the 6 inch flex? Am I missing the point by asking if I should insulate under the top cap to keep the cold outside? As long as the transfer of heat is safe. Then the only reason to insulate is to maintain higher flue temps, correct? Will insulating to keep the cold outside help with this? Or is that just a waste of time and money?

 

[bholler]

Clay liners are an exemption clay liner need that stated clerance if not you need a linertested to ul-1777 and rated for use in a chimney in contact with combustibles which means insulated

 

[frankinri]

Clay liners are an exemption clay liner need that stated clerance if not you need a linertested to ul-1777 and rated for use in a chimney in contact with combustibles which means insulated

So the clay liner needs to be at least 2 inches from combustible materials? This is what I have

 

[bholler]

No there needs to be 2 " from the outside of the chimney to combustibles for an interior chimney

 

[frankinri]

No there needs to be 2 " from the outside of the chimney to combustibles for an interior chimney

How is that possible it would have to float all the way to the roof? This chimney being interior is in walls and passes through the roof. Is there somewhere I can read about this? I'm quite lost

 

[bholler]

It pretty much never happens that is why i always say insulate everything. That code is straight out of the irc book they give all the required clearances there

Here is a decent page about it to. http://www.rumford.com/code/clearances.html

In the 7 years i have been working on chimneys i have only seen one interior chimney that had proper clearance out of many hundreds of chimneys i have looked at. Proper clearance on exterior chimneys are more common but still not the norm.

 

[frankinri]

It pretty much never happens that is why i always say insulate everything. That code is straight out of the irc book they give all the required clearances there

Here is a decent page about it to. http://www.rumford.com/code/clearances.html

In the 7 years i have been working on chimneys i have only seen one interior chimney that had proper clearance out of many hundreds of chimneys i have looked at.

Being clay lined don't I meet this;

"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."

And if not once I install this I would be correct
http://www.woodlanddirect.com/Chimn...mney-Champion-Easy-Flex-Chimney-Liner-Kit-6in

It says it's listed ul 1777

 

[bholler]

No clay liners are not listed and yes that liner is An olympia liner ( that they are not authorized to sell and yes it is ul listed for zeroclearance with insulation. And the instructions will tell you that as well as if you read the listing for ul-1777. The instructions will also say thet if it is not insulated the ul listing is void.

 

[frankinri]

No clay liners are not listed and yes that liner is An olympia liner ( that they are not authorized to sellaaaaaaaaaaaaaaaaaaa0 and yes it is ul listed for zeroclearance with insulation. And the instructions will tell you that as well as if you read the listing for ul-1777. The instructions will also say thet if it is not insulated the ul listing is void.

Ok so that liner is not ul 1777 unless it's insulated?

 

[bholler]

Yes and i have no idea what happened there with all of the aaaaaaaaaas i edited it

 

[frankinri]

Yes and i have no idea what happened there with all of the aaaaaaaaaas i edited it

Ok thanks. You saved me from an uninformed bad decision. I guess I will have to go with the pre insulated 5.5 inch pipe like others have recommended