Mineral wool chimney liner insulation?

[fishinhunter12391]

Hello all, new member but have been viewing for some time now. Im new to fireplace inserts and have ordered a drolet 1800i insert and a chimney liner. But have since read a number of post saying to insulate the liner. Now granted my chimney in in between my attached garage and house and home is a ranch with maybe a 20ft at most stack height so from what I've read insulating probably is not necessary with my setup but I would like to get the best draft possible on a budget so my question is can I drop/ tamp down mineral wool insulation down my clay flue around the liner? Says it is good past 2000degs? So I guess I don't see a reason why I couldn't, but just wanted to bounce this idea off you guys. I searched the site and all I could find is using it around the insert. Which I'm also curious what the point of that is as well. Thank you in advance for any input you can provide. Tyler

 

[weatherguy]

Some people have done it that way but only because they didn't wrap the liner before installing. Is it that expensive to get insulation to wrap around the liner? I think since you're chimney is between an unheated space I would insulate. You will need a block off plate before you pour any insulation down but you should have one anyway, they're cheap enough to make.

 

[fishinhunter12391]

Some people have done it that way but only because they didn't wrap the liner before installing. Is it that expensive to get insulation to wrap around the liner? I think since you're chimney is between an unheated space I would insulate. You will need a block off plate before you pour any insulation down but you should have one anyway, they're cheap enough to make.

I guess my thinking of price is the $255 online for the insulation kit or 60ish bucks to fill the void with mineral wool that I can pick up at Menards. I plan on doing a block off plate that you stated. Thank you for the info!

 

[branchburner]

Welcome to the forums. One thing to consider: your liner will list "approved" methods of insulation, and any other mode of insulation will not technically be in compliance with the product specifications, and thus may not technically be in compliance with code.

That said, I insulated my liner with perlite (with rock wool at the base of the liner, to keep the perlite in)... that might even be a few bucks less than your method, and also give a more uniform insulation than trying to stuff rock wool evenly the entire length of the liner.

You could also just use the rock wool for a few feet at the base of the liner and above the roof line, rather than the entire length, as many people seem to do.

 

[fishinhunter12391]

Welcome to the forums. One thing to consider: your liner will list "approved" methods of insulation, and any other mode of insulation will not technically be in compliance with the product specifications, and thus may not technically be in compliance with code.

That said, I insulated my liner with perlite (with rock wool at the base of the liner, to keep the perlite in)... that might even be a few bucks less than your method, and also give a more uniform insulation than trying to stuff rock wool evenly the entire length of the liner.

You could also just use the rock wool for a few feet at the base of the liner and above the roof line, rather than the entire length, as many people seem to do.

Thank you for the info! Just to clarify when you say perlite, is this being used as a loose fill with nothing mixed with it? Unlike vermiculite with the Portland mixed in because the wet mix method I can foresee being a mess not to mention if you need to replace the liner for whatever reason. Also when you say you used mineral wool at the base is that is just jamming some up the flue for a plug? As to insulating the top and the bottom as stated that's basically just blocking the air void between the top and bottom of flue with no insulation in the middle correct? Thanks for bearing with me.

 

[ddddddden]

. . .when you say perlite, is this being used as a loose fill with nothing mixed with it? Unlike vermiculite with the Portland mixed in because the wet mix method I can foresee being a mess not to mention if you need to replace the liner for whatever reason. . .

I think most folks who go this route do the dry fill. I have the impression that the wet mix is more of a pro job.

Also when you say you used mineral wool at the base is that is just jamming some up the flue for a plug?

Yes.

As to insulating the top and the bottom as stated that's basically just blocking the air void between the top and bottom of flue with no insulation in the middle correct?

Yes, dead air space in the middle, with the plug at the top filling the entire portion of the chimney that is above the roof line -- the coldest part of the chimney.

Personally, I see the appeal of a quick & dirty plug, but I can't see messing with dry/wet fill when you could get a pre-insulated liner (wrapped with mineral wool at the factory) for ~ $500. I did this + plugs at the top & bottom to help stop air loss from the house.

 

[fishinhunter12391]

I think most folks who go this route do the dry fill. I have the impression that the wet mix is more of a pro job.
Yes.
Yes, dead air space in the middle, with the plug at the top filling the entire portion of the chimney that is above the roof line -- the coldest part of the chimney.

Personally, I see the appeal of a quick & dirty plug, but I can't see messing with dry/wet fill when you could get a pre-insulated liner (wrapped with mineral wool at the factory) for ~ $500. I did this + plugs at the top & bottom to help stop air loss from the house.

Thank you for the clarification on that matter. Very helpful. In your opinion is it unsafe to do what I have previously stated with the mineral wool by dropping very small pieces of it down in between the upper and lower plugs you guys have stated? Thanks

Edit: Just for peace of mind I'd like to make sure what I'm planning on using is the same thing as what we're calling mineral wool as I've heard it called rock wool ect. Thanks again http://www.menards.com/main/mobile/...-mineral-wool-insulation/p-2045736-c-5780.htm

 

[branchburner]

Nothing unsafe... just two things to consider:
1) This method will provide uneven insulation to various parts of the liner, thus meaning:
2) This method will not be to code, which may have potential ramifications for insurance/inspection

(A note: on my liner, I DID use a bit of wet mix at the base, just to ensure the perlite did not sift through.)

 

[ddddddden]

I agree. Not unsafe, just a question of how uniformly you can put the stuff down the entire chimney + over time, it will settle. . .probably doesn't matter that much, since most of your chimney is enclosed in the garage. I would focus on the portion of the chimney above the roof line, where it's exposed to the weather.

As for mineral wool, Roxul seems to be the most popular brand, but the Thermafiber you posted looks similar. If you really want to get persnickety about it, ceramic stuff like Kaowool is supposed to be the best, but ceramic fibers are smaller and more of a respiratory hazard than mineral wool fibers, which are also not desirable to breathe, so you'll want to seal this off well from your living space.

https://www.hearth.com/econtent/index.php/articles/making_a_block_off_plate/

https://www.hearth.com/talk/threads/is-kaowool-asbestos.37622/

https://www.hearth.com/talk/threads/insulation-around-an-insert.51972/

https://www.hearth.com/talk/threads/rockwool-where-to-buy.27207/

 

[JayD]

You can also buy Rockwool at all Hydroponics stores. Blocks of different sizes and loose bags Jay

 

[fishinhunter12391]

I agree. Not unsafe, just a question of how uniformly you can put the stuff down the entire chimney + over time, it will settle. . .probably doesn't matter that much, since most of your chimney is enclosed in the garage. I would focus on the portion of the chimney above the roof line, where it's exposed to the weather.

As for mineral wool, Roxul seems to be the most popular brand, but the Thermafiber you posted looks similar. If you really want to get persnickety about it, ceramic stuff like Kaowool is supposed to be the best, but ceramic fibers are smaller and more of a respiratory hazard than mineral wool fibers, which are also not desirable to breathe, so you'll want to seal this off well from your living space.

https://www.hearth.com/econtent/index.php/articles/making_a_block_off_plate/

https://www.hearth.com/talk/threads/is-kaowool-asbestos.37622/

https://www.hearth.com/talk/threads/insulation-around-an-insert.51972/

https://www.hearth.com/talk/threads/rockwool-where-to-buy.27207/

Thank you all for the information and thanks for the links. This was all very helpful. Tyler