Liner Insulation Question

[AbeAinPa]

Couldn't find this via search.

I'm installing a full length liner with wrap insulation and have a question as to where the insulation should terminate on each end. My application is a 21' flue located centrally. Should the liner insulation go all the way to the top plate on the upper end and stop at block off plate on the lower end? Any additional insulation on either end beneficial? Any input would be greatly appreciated.

Thanks

 

[RAY_PA]

thats pretty much what I did...I think I stopped 6 inches short of the top plate and blockoff plate....I dont know if thats how its 'supposed to be', but worked for me

 

[Ivy Frank]

It's great that you're insulating it - that's the way to go.

I wouldn't worry about the last 6" - wrap it if you can, but in the end, the performance difference will be small.

 

[burntime]

I wrapped everything in the chimney from top plate to block off plate. That way masonary is warmed as well by the liner. The difference with and without the liner is pretty drastic...and I have an internal chimney. I also did the block off plate. You are smart doing it right the first time!

 

[AbeAinPa]

Thank for the input, appreciate it.

Has anyone ever use left over liner wrap to insulate either or both sides of their block off plate? Good idea?

 

[scotsman]

I have a question for this thread:

I have double walled pipe with 8" inner SS flue pipe surrounded by 11 or 13" galvanized pipe with an airspace between. I plan to install a 6" SS liner inside the 8" SS. The existing flue pipe is interior to the house and connected to ZC FP at present.

The question is: Insulate the 6" liner or not? Anyone have this arrangement? With all this pipe and air space, would insulation be needed/necessary/good idea or not AND why? Been told that no official testing has been done with such an arrangement and I cannot find any published information regarding same.

Can any of you professionals contribute some guidance? The difference is that if no insulation is needed, I can proabably do the install myself. If it IS needed, I for sure won't be doing it. I'm too new to understand the physics of such a flue piping arrangement and don't want to blindly do something that may come back to haunt me later.

Also, since we're out in the county, would it be a good idea to require any contractor to meet the requirements of our insurance company for installation and or have the insurance company approve it? Anyone ever done that?

I am waiting on the stove and collecting wood . . . LOTS of wood!

Sure appreciate any input. Thanks--

 

[AbeAinPa]

Since the insulation kit that came with my liner is more than I will need to use for wrapping the liner itself I was thinking about using the excess on the block off plate. Anyone have an opinion as to whether or not this is a good or bad idea? I was even thinking of perhaps applying it to both sides.

 

[bren582]

Insulate the top of the block off plate if you have the extra liner insulation left over. Can't hurt.. Its the law of diminishing returns thing, small benefit but a benefit none the less. 90% of the benefit is sealing the flue so hot air is forced back into the room versus going up the flue and in the case of an exterior chimney being wicked out to the outside. No need to insulate the bottom or firebox facing side of the plate..

 

[oconnor]

I have a question for this thread:

I have double walled pipe with 8" inner SS flue pipe surrounded by 11 or 13" galvanized pipe with an airspace between. I plan to install a 6" SS liner inside the 8" SS. The existing flue pipe is interior to the house and connected to ZC FP at present.

The question is: Insulate the 6" liner or not? Anyone have this arrangement? With all this pipe and air space, would insulation be needed/necessary/good idea or not AND why? Been told that no official testing has been done with such an arrangement and I cannot find any published information regarding same.

Can any of you professionals contribute some guidance? The difference is that if no insulation is needed, I can proabably do the install myself. If it IS needed, I for sure won't be doing it. I'm too new to understand the physics of such a flue piping arrangement and don't want to blindly do something that may come back to haunt me later.

Also, since we're out in the county, would it be a good idea to require any contractor to meet the requirements of our insurance company for installation and or have the insurance company approve it? Anyone ever done that?

I am waiting on the stove and collecting wood . . . LOTS of wood!

Sure appreciate any input. Thanks--

The main code reason for insulation is in sutuations where the existing flue being relined doesn't meet code requirements, like when a brick flue built for oil burning is now connected to a wood appliance. Insulating the liner as per instructions can give you a zero clearance flue - no need for clearances to combustibles outside the chimney (brick oil flues don't need clearances, but wood needs 1 or 2 inches, depending....)

As for testing of a given install, if you look around you can find liners tested for install into larger prefab SS chimneys, or ZC flue setups. This is where the rub is - the only "right way" to insulate a liner is IAW the instructions that the liner manufacturer gives you. Those instructions are tested by a lab to the UL1777 spec, and each test is money. So a small producer may not test the liner for insulation at all, and a large manufacturer may test lots of install variations - that doesn't mean one is safer than the other, just that one has been tested in a given install, and the other wasn't.

In the end, liners were originally meant as replacements for clay tile in brick chimney. Adding a stainless liner did not change the need for the brick chimney to meet code. Insulating the liner may reduce the clearances required for a chimney to meet code, and only the manufacturer of the liner can give you the "offical" way to do it. Doesn't mean other methods or applications won't work or aren't safe, they just aren't tested - maybe they are safe, maybe not.

As for your contractor, I would specify that all the work must meet the requirements of code (the "authority having juristiction" is the term I see used by US members). Your insurance company is likley going to want to know that someone who is trained has inspected it, so the certifications of the installer or inspection agency. BEWARE though, lots of certified trained installers and inspectors mess up jobs - you know your home better than they do. Get your research done, and spell out what you want in detail.