How much is too much

[BCPerson]

In Googling I find much advice about too much creosote
causing chimney fires.
What exactly is "too much" ?

I've just cleaned the loose soot out of my chimney
and what's left are large patches of glaze about 1/16"
thick.
I know that the cleaner the better but should this small a
build-up be a concern?

Thank you

 

[oldspark]

IMHO no, the black runny stuff is the worst with the glaze and sooty looking material being normal for a chimney being burnt correctly.

 

[rdust]

I've always heard a 1/4" or more needs to be swept. Obviously none is best, if it's dry and doesn't look like tar I'd guess you'd be fine.

 

[begreen]

Stage 3 creosote (hard glaze) should not be ignored. It can be the most serious from what I've read. Maybe start using some ACS to break it down?

http://www.chimneycricket.com/chimney-deglaze.htm

 

[oldspark]

Stage 3 creosote (hard glaze) should not be ignored. It can be the most serious from what I've read. Maybe start using some ACS to break it down?

http://www.chimneycricket.com/chimney-deglaze.htm

Interesting, the hard glaze I have seen in my chimney is right at the top so is not a big deal but it looks like if you have a lot it could be a problem but it would be nice to have a second opinion as they are trying to sell you something.

 

[begreen]

I just gave that link for the photos. There are several. Google - creosote stages - for more info.

https://www.hearth.com/econtent/index.php/QA_Templates/info/2087/
http://askthechimneysweep.com/2009/03/creosote-problems/

If the glaze is just showing up in the upper foot or so, it's not as big a deal. How is the wood that is being burned? Very well seasoned?

 

[BrotherBart]

Stage 3 glaze creosote makes a really mean chimney fire. And I ain't selling anything. I lined these chimneys and started burning dry wood to stop having those chimney fires.

 

[oldspark]

I did a google search for creosote glaze and come up with all sorts of links, sound like it needs to be taken care of one way or the other.

 

[firefighterjake]

General rule of thumb I give folks is 1/4 inch or more and folks should be sweeping . . . as mentioned the "best" creosote to have (if there is such a thing as "good" creosote) is the fluffy, popcorn or corn-chip like stuff . . . the runny stuff is just plain messy and the glazed stuff is not all that good.

 

[Fsappo]

Stage 3 glaze creosote makes a really mean chimney fire. And I ain't selling anything. I lined these chimneys and started burning dry wood to stop having those chimney fires.

I agree. The concentration of energy in even a little bit of the glazed stuff is scary. If I had large areas of the shiny stuff, I would be using the ACS that BB mentioned and cleaning the chimney till it was gone. After that, I would use a good quality epa certified wood stove with seasoned wood and good burning practices so it never happened again

 

[Battenkiller]

I have asked about the BTU value of creosote online & gotten no responses so far, from scientific forums, but I would bet the glaze would have a similar BTU content as coal, maybe.

Probably much higher than coal.

Based on the average composition of wood creosote (guaiacol, cresols and other phenolics), I think it might be up there with gasoline at around 20,000 BTU/lb. Plus, glaze creosote is denser than gasoline by a stretch, so any measurable accumulation will pack a very potent wallop if ignited. Best bet is to get rid of it chemically and make sure you burn hotter in the future. Low temperature burns - for whatever reason among many that they may occur - are the Numero Uno player in the development of intermediate products of combustion in wood fires. Creosote is merely one of these intermediate products. A small, intense fire will burn much cleaner than a large fire that has the air drastically reduced.

Don't count on your magic EPA stove to automatically burn all of the s*** away. That only happens during controlled testing. In real life, it's better to burn it away in the primary combustion rather than counting on the secondary combustion to clear up all of the smoke you shouldn't be making in the first place. Burn hot. Best done with dry wood and ample air within the burn zone. And stop bragging about your extremely long burn times, they are only possible by creating the very conditions that are best for creosote formation. ;-)