insulating a chimney liner?

[trx680]

is it really worth it?

what purpose does it really serve?

I might be installing a rectangular liner and am wondering about insulating it

Will be for a Buck 91 woodstove.

 

[bholler]

is it really worth it?

Yes

what purpose does it really serve?

It is required to meet ul requirements and unless you have the proper clearance to combustibles it is also required by code

 

[TedyOH]

I've always wondered about this "code" requirement - this is how my simple minds sees this, in my house anyway;

Had an open fireplace that held a lot of burning wood, probably 4 times the amount of wood, than the now installed insert holds. Most of that open fireplace heat was blasted up the tile lined chimney. I understand the need for a liner for an insert or stove to run properly, but, why would the insert and liner make the chimney hotter or more dangerous? I would expect the opposite, the clay liner in the chimney would have to be cooler, cooler then what it was when the open fire was blazing away.

Can someone explain this a little better, why the insert and liner makes the chimney hotter and why the "all of the sudden the need for additional clearances"?

Thanks!

 

[Grisu]

cooler then what it was when the open fire was blazing away

A misconception. The inrushing cool room air that goes up the chimney will cool the fireplace exhaust more then the slow moving exhaust from an insert which can be rather hot during the early burn.

why the "all of the sudden the need for additional clearances"

There is no need for "additional" clearances when installing an insert. The problem is that most masonry chimneys have been built before code required 2" clearances to all combustibles (or were built ignoring that requirement). You are simply making the chimney compliant with current code when installing an insulated liner.

An insert is also anticipated to run more often and has the potential to accumulate more creosote than an open fireplace. An insulated liner will offer way more protection than a simple clay liner when a chimney fire occurs.

 

[TedyOH]

Thanks Grisu - so basically you are saying that insulating the liner will make you compliant to code in case your original clay liner chimney was not to code?

I skipped the insulation on my liner, my chimney has two 12 x 12 clay flues, one was for the fireplace the other is for the furnace and hot water tank, only about the last 10' is exterior exposed, no drafting issues so I'm guessing my $400 savings choice was the right choice? 2 story colonial built in 1979.

 

[Grisu]

Thanks Grisu - so basically you are saying that insulating the liner will make you compliant to code in case your original clay liner chimney was not to code?

That, but it will also keep the flue hotter for better draft and less creosote accumulation.

I skipped the insulation on my liner, my chimney has two 12 x 12 clay flues, one was for the fireplace the other is for the furnace and hot water tank, only about the last 10' is exterior exposed, no drafting issues so I'm guessing my $400 savings choice was the right choice?

Can you say putting all-seasons on your car and skipping the winter tires was the right choice? As long as you don't have an accident you may assume so.