How much creosote is "a lot"? And what temperature does single wall flue start to glow?

[tradergordo]

I decided to disassemble my flue and sweep my chimney for this first time this weekend since I'm a new wood burner this year and I now know that in the first month I was not burning hot enough and some of my wood is not seasoned enough. The Rutland poly brush works very well by the way. Most of the accumulation was right around where the chimney exits the house (first cold outside part). Anyway, between both the flue and the chimney I'd estimate there were about 4-6 loose cups of debris - I don't really know the difference between "soot" and "creosote", it all looked like "black stuff" to me. Anyway, since I haven't even had all that many fires this seemed like a lot of junk to me. Is it?

By the way, for anyone using a spark arrestor in their chimney that you installed yourself (like the Lowes/Home Depot stuff) one problem that I discovered during my inspection/sweep was that the spark arrestor screen was creating excessive blockage (covered in soot/creosote) due to unnecessary overlap of the metal mesh. My guess is that they either only make one size (for 6" and 8" caps) or they sent me the wrong one - there shouldn't be much if any overlap on that metal mesh. I disassembled my cap, removed the spark arrestor, cleaned it, and cut it to the proper size with no overlap.

Interestingly enough, the very next day my wife decided to make a fire using the driest, smallest splits we have, filling the box with wood. I noticed it burning very intensely and a lot of heat coming from the stove so I asked her what temp the flue thermometer was at - was pretty shocked when she said 1200! I've never burned that hot before. Was glad I swept the chimney the day before (then again that fire probably would swept the chimney for me).

I didn't know it could get that hot with all doors securely shut (though primary air was full and bypass damper was open). Nothing was glowing though (flue or stove) - maybe because it was only at those temps for a little bit - but I was wondering if anyone knows what temp single wall flue pipe does start to glow? After turning down the air and closing the damper it quickly went back down to a more normal operating temperature.

 

[Eric Johnson]

It'll glow when the creososte that's accumulated inside ignites. I've had it happen more than once--no harm done, but no fun to watch, either.

"A lot" of creosote is when the pipe and chimney are full of the black stuff. A couple of cups is not very much. That's about what you should get in an average cleaning, in my experience. Depends on the installation, of course.

I take the spark arrestor screen out of the cap.

Once the cold weather starts you'll probably have less creosote on average. Warmer weather tends to make people damp down their stoves, thus cutting the draft and encouraging the growth of creosote. When it's cold out, you regularly fire up good, and that will burn off a lot of it. When you get a hot chimney and the brown smoke out of your chimney, you know your chimney is cleaning itself.

You don't hear it much anymore (with all the clean-burning stoves being used) but the best advice back in the day was to burn at least one hot fire every day to keep creosote accumulation down. Most of us would do it first thing in the morning.

 

[BrotherBart]

Well, I can tell ya that the top and flue collar of a 5/16" thick plate steel stove start glowing between 1,100 and 1,200 degrees. Of course you won't see it right away if the lights in the room aren't dim. The light show temp for 24 gauge pipe is probably about the same.

 

[Andre B.]

Color Temperature chart.
http://www.muggyweld.com/color.html
____________
Andre' B.

 

[quads]

It depends on the type of creosote. The slick, shiny stuff is really bad and is the stuff chimney fires are made of. A good glazing of it is a lot. The crunchy, brittle, flaky stuff isn't so bad. You can have a pail full of that stuff and not worry too much as long as it isn't blocking the pipe/chimney. It is all mostly black, except the really wicked slick, shiny glazing has a brownish tint to it.

Next time I clean my chimney I will snap a few pictures of the different types of creosote, if I remember. Unless it's already been done? I usually have a little of each!

 

[BrotherBart]

Color Temperature chart.
http://www.muggyweld.com/color.html
____________
Andre' B.

Oh well heck. I had a long way left to go yet before "lemon".

 

[suematteva]

Color Temperature chart.
http://www.muggyweld.com/color.html
____________
Andre' B.

Oh well heck. I had a long way left to go yet before "lemon".

Good chart...I thought it was lemon as in the color your drawers would be if it got that hot!!

 

[BrotherBart]

Color Temperature chart.
http://www.muggyweld.com/color.html
____________
Andre' B.

Oh well heck. I had a long way left to go yet before "lemon".

Good chart...I thought it was lemon as in the color your drawers would be if it got that hot!!

That happened at exactly 975 degrees farenheight.

 

[wg_bent]

When I cleaned mine I only got a little of the really black stuff at the very top. The rest was more like a mix of black and grey ash. When touched it felt like ash. I got about 3 cups out of my cleaning in a 23' chimney liner.

 

[Eric Johnson]

You be doing good, Warren.

One weekend, many years ago, I decided to clean out the chimney and the pipe connecting my boiler to the chimney. It's always a good idea to take the pipe off the stove to clean out the ash shelf. Anyway, I was banging on the galvanized elbow, trying to knock some of the crap loose, when the section of pipe I was hitting shattered, leaving me with a big, old gaping hole in the elbow.

Apparently that stuff gets brittle over time. Probably after too many glowing red sessions.

 

[suematteva]

You don't hear it much anymore (with all the clean-burning stoves being used) but the best advice back in the day was to burn at least one hot fire every day to keep creosote accumulation down. Most of us would do it first thing in the morning.

We have continued to do this with our non cat for the last 4 years we have run it. I did not know it was no longer necessary "per se" with the newer technology stoves. Just learned it the other day when Todd brought it up in another thread...Was regular procedure with the pre EPA stove and just kept on with the mansfield.

That being said will continue, after 5 cords of 2 yr old wood and 1 annual brushing had about a 1/2- 3/4 cup of the dry greyish brown stuff.

 

[tradergordo]

I don't remember seeing ANY of this greyish, slick, shiny stuff. Mostly I just noticed the black, crunchy, flakey stuff. I've heard about the "one hot fire a day" thing - but have been wondering what exactly qualifies? Do you bring it to a certain temp, and how long do you keep it at that temp?

 

[BrotherBart]

You don't hear it much anymore (with all the clean-burning stoves being used) but the best advice back in the day was to burn at least one hot fire every day to keep creosote accumulation down. Most of us would do it first thing in the morning.

We have continued to do this with our non cat for the last 4 years we have run it. I did not know it was no longer necessary "per se" with the newer technology stoves. Just learned it the other day when Todd brought it up in another thread...Was regular procedure with the pre EPA stove and just kept on with the mansfield.

That being said will continue, after 5 cords of 2 yr old wood and 1 annual brushing had about a 1/2- 3/4 cup of the dry greyish brown stuff.

I am with you. I want to see that 700+ degree stack temp once every morning.

When I cleaned the liners last week I just did one pass through since I am going to be checking them regularly with the new stoves. For fifteen or twenty minutes after I started the stoves up brown dust blew out of both chimneys. It reminded me of what Eric J said his dad says. "You want your creosote on your neighbors car, not in your chimney.". Greatest wood burning line of all time.

 

[BurningIsLove]

For my DW, I make sure the magnetic thermometer on top of my single flue reads 600+ for at least an hour after a cold start before I damper down...but usually once the reburner & stack are up to temp, it rarely reads below 525 anyhow. I dont think I've ever seen my flue glow before, and the thermometer has read around 800 before.

Tradergordo, I had the same experience about 2 weeks ago w/ my cleanout (I was simply too busy to post). I opened up the cleanout door at the bottom of the stack in the basement, and to my alarm I had several cups of small, black matter. It was mostly dull, tiny flakes with a few small chunks. A few more shiny pieces, but definitely they were the minority component.

 

[Eric Johnson]

Funny thing about creosote: Try burning some with a match or a lighter some time. It won't ignite. But torch a load off in a chimney, and you'll know you should have cleaned your chimney last weekend instead of going fishing.