the liner insulation question

[kerryb23]

okay, folks

getting a new stove in a week. englander 13-nc. current set up is a cheap boxwood installed with six inch stove pipe inserter into thimble, through brick directly into masonry (unlined) chimney. i got creosote out the butt, especially up near the top of the chimney. the installer called my current installation (which was done by supposedly certified sweeps) "interesting. and sort of dangerous." he wants to install a liner, which i'm all for. i'm looking at $600 for the stove, $800 for equipment and labor. $500, $300 respectively. it's going to take a good portion of the savings but i think for safety reasons, it's worth it. however, in addition to the liner, he wants to install a fiberglass insulation between the exterior of the liner and the masonry. this is his reasoning: "you've got a lot of creosote. it's almost impossible to remove. i can use some chemicals, but it might not get it all. the insulation will prevent any heat from the liner igniting the cresote, therefore igniting the chimney and possibly your house."

now, generally i have a pretty good b.s. detector. i'm wondering, is it really so impossible to clean out creosote? i mean, isn't that what sweeps and their tools are supposed to accomplish? i'm not sure how much this insulation is, even if it's $100 or so, that's not really a huge extra cost in the scheme of things, so i'm sort of willing to not even bring it up. but am i being bulled a little bit here? just looking for comments and opinions. thanks, everyone.

 

[edthedawg]

Creo is a major pain to clean. What's the setup - exterior chimney? How big? clay tiles or just a bare brickwork chase?

It's not completely illogical to think his way, esp if it's a major creo buildup. But it's also the first time I've ever heard anyone to demand an insulated liner just for this reason... Willing to bet others here might have...

 

[rydaddy]

Edthedawg hit the nail on the head. In general I would say the consensus is that an insulated chimney liner will draft better? But saying that it is "necessary" is a little questionable. Very situaiton specific. Also, if you read on here enough... as I have found out myself, your chimney is equally if not more important than what stove we have.

 

[thechimneysweep]

Reading between the lines a bit here, it sounds like you might have glaze creosote deposits in your flue (hence the need for chemical removal). When glaze first forms, it is very wet, and can soak into the unprotected mortar joints in an unlined chimney, where it can't ever be completely removed, even with chemical treatments.

Sounds to me like your Sweep anticipates having some soaked-in glaze remaining when he's done cleaning your chimney, and wants a barrier of insulation between it and the hot liner pipe to prevent future ignition. I'd go along with his plan, but wouldn't use fiberglass. As a Sweep, he has access to ceramic blanket (Kaowool), and Forever Flex's Super Wrap, which are much better options for this application.