Why is it possible to OVERINSULATE a flue liner?

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Pen - that is absolutely true, I noticed Selkirk also had that requirement to honor their warranty.
 
Yeah I have seen that from some companies and even as a pro who that benefits I think it is a load of crap.
 
Installing any manufactured product is always a matter of following instructions. I wouldn't go as far as saying no liners use loose fill insulation (I haven't read ALL the manuals out there).

It's not just a fireplace thing either. Think of all the products that go into a home - building code can't cover them all, so testing I'd done. Testing is expensive, so you should expect to post more for a product with multiple approved install methods.

I have even come across a liner company at one point that didn't seem to have any UL or other testing despite using the labels on the products. They had the manufacturing ability and made liners the same way everyone else did. They were likely just as safe physically, but the apparent lack of testing made my skin crawl.
 
I haven't read all the manuals either but I have had quite a bit of professional training and used allot of different liners and it is pretty much industry standard not to use loose fill due to the settling factor. The cement and vermiculite mixes are tested with a large percentage of the liners out there though.
 
over time it would settle and pack in at the bottom not allowing the liner to expand and contract

Not sure I understand this... how would a cement and vermiculite mix allow more expansion than loose fill alone?
 
it doesn't set up hard if you have ever worked with it you would know and when the vermiculite settles to the bottom and gets packed it in it gets hard as a rock and doesn't move at all.
 
Makes sense. When contacted they could provide no technical reason.
You wanted 'legal' not 'technical' support.
The former could give you an answer.
 
Forgive my ignorance, im new to wood stoves and dont even have mine installed yet. (We are in the decision making process) but....when you install a chimney you have to pour insulation into it? I thought you assembled the chimney sections and they came ready to use. No?
 
when you install a chimney you have to pour insulation into it?

No, it is just one of several possible methods to insulate a liner within an existing masonry chimney (if that is desired/required), and is actually used pretty rarely.
 
I think creek heat is talking about a class a chimney by what he said and yes those are preinsulated and ready to go. And pour in is used pretty commonly in some areas. It is rarely used in insert installs those are usually wrapped.
 
Trouble with pour-in is, when a minimum of 1’’ of mix is required around the entire liner to obtain the zero clearance rating, how do you center the liner in the chimney (especially one with any offsets) and absolutely ensure that the mix has one inch in thickness at every point all the way around the liner for its entire length? Even one spot where the one inch was not acheived would mean the liner was not technically to code.
 
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