Total creosote clog and CHIMNEY FIRE: THREE WEEKS after brand-new install?!

[Toba Guy]

Hello Folks,

OP back again.

This is a bit of an epic post, so stick with me.

So I agreed with those of you who figured it was a bit jumping to conclusions to try and fully diagnose off one load of poplar (the previous test-fire). Especially seeing as how I didn't load it as I usually would for a cold stove (with some scrap between the kindling and cordwood). I must have misunderstood, I thought we were doing some weird test-fire without any scrap to take that aspect out of the equation. I think we can more or less ignore those previous results, considering what happened with the poplar load below.

Test fire #1: "25% scrap, 75% poplar" as suggested by Jags

load consisted of paper, bark, 4 pieces foot-long pieces of scrap 2x4, 4 normal-sized splits of poplar

In the last test-fire, we had already established that the poplar didn't produce black-smoke and would quit smoking completely once up to temp, so I didn't bother running in and out to check the chimney as often, same results as the last test burn, some smoke at the start-up, but once up to temp, no problems, only heat-mirage at the cap.

0 minutes: lit the fire

6 minutes: stove temp (measured by IR thermo at upper left-hand corner of griddle) up to 350 F. Stove is chugging air hard, so I shut off the ignition air.

8: 500 F so took the primary air down to 5-10%

10: 525 F

15: 600 F so took the primary air down to minimum

17: 650 F

23: 665 F

27: 685 F

30: 700 F

34: 725 F

36: 750 F Fire was drawing like crazy, flames whipping around, despite being choked back as far as possible. Since the temperature was still climbing, I became worried about over-firing the stove, but with the primary air already at minimum, my only option was to close the window and induce a negative-pressure in the basement, so I did. It helped immediately with the draw, and the temperature began to fall soon after.

40: 765 F

43: 725 F

45: 700 F

1 hour and 25 minutes: 500 F

So I don't know if this is a normal situation with poplar of 18% moisture (this is only the second time I've burnt this species), but I was concerned over the possibility of over-fire. I know Jags, you said to keep it below 700 F. Made me wish I still had the flue-damper installed. Also makes me wonder what would have happened had I already had the new combustion-air to the furnace and fresh-air intake for the basement already installed (happening this Saturday, to resolve the negative pressure issue), and thus no ability to close the window and cut air to the stove further.

- What is the max safe temp for the stove?
- What peak temperature should I be shooting for?
- Should I have been able to control the fire more easily or is this the way it goes? (Had I been loading onto an established coal-bed, say before turning in for the night, I could easily have packed the stove way more. Does this mean I can't load the stove fully with poplar alone? Need to mix in some Oak etc?).
- Suggestions / insights I'm not cluing into see as how I'm a first-time burner?


I also did another test-fire with the 9-12% moisture pine:

Test fire #2: Can I get the pine to burn without black smoke?

After having "burning-tires" amounts of black smoke when burning a load of only smaller pine-splits, despite good temperatures reached, I wanted to see if I could burn smaller numbers of larger pieces of pine and have a clean burn (thus testing out the excess-gases-condensating theory).

Load was paper, bark, two 15" pieces of scrap 2x4, and 2 larger-sized pine-splits.

Here is what happened:

0 minutes: lit the fire.

5 minutes: 250 F

8 minutes: 425 F, drawing well, but not chugging like the previous time. But up to temp so I cut the ignition air. Some grey smoke at the chimney still.

11 minutes: 475 F

12 minutes: 500 F

14: 525 F. Less grey smoke at chimney, but some still visible. Cut the primary air down to 5 - 10%.

20: 550 F. No smoke at the chimney, only heat-mirage.

25 minutes: 535 F. Still clean-burn at the cap.


So correct me if I'm drawing the wrong conclusion, but looks that the previous times with black-smoke was likely due to the 2ndary tubes being overwhelmed with excess particulate / gases?
Is this what the installer was talking about regarding the pine being "punky": Too dry and burns too fast?

What else should I be pulling out of this test-fire?

Suggestions for future loads, combinations of species to balance things out further? Or test things further?


I'm just glad I've found a way to cleanly burn that cord and a half of pine I have sitting in the garage.


Thanks for reading this epic post,
And being so generous with your time and experience this past week.

 

[jatoxico]

Off hand that sounds like good progress and yes I think the pine was outgassing. Once the pine got get fully involved with fire caused massive amount of gas to be released and overwhelmed 2ndary burn capacity.

I would also wonder that now you are getting more familiar if you could start shutting air earlier to minimize peak stove temp and maximize cruise temp. May not really need to even use startup air most times and start cutting primary sooner.

As far as wood types you'll get a feel but that pine has a place just may need to use it over time as a mix in. Great to have as a mixer when you're stuck with marginal hardwood. Matter of trial and error but there are also things you can do as far as E/W or N/S loading, split size and packing depending on if you're going for short hot fire or longer burn more moderate burn.

 

[begreen]

Another control factor would be the size of the splits. Larger splits = slower burn. And there is the air between splits. Tighter packed fires will burn slower.

 

[Plow Boy]

I'm concerned with the fact the flames where still very active with the primary air closed off. On my stove as soon as I close primary air I can see the effect on the fire , sounds like an air leak or really strong draft issue.

 

[Jags]

I will have to admit that I have had my stove at 850F+. Not proud of it, but it has happened. Your peak temps didn't hurt the stove a bit, but I would be looking at ~750 as the ceiling goal with a cruise temp from 500F to 650F. A bit higher won't hurt things, but unless you are at the coaling stage I wouldn't dip much below 500F or you might start to see smoke again.

Sounds like you are starting to get the hang of things. BG is correct - split size matters. You are running a big stove. Run big splits. With 18% popular it doesn't really surprise me that you would have a whiplash effect on the temps. Start cutting the primary air back a bit sooner with that wood.

Now that you have a base line to work with as far as stove performance goes - you can tweak your methods. This is part of the "learning curve". Every stove has one and every install is a bit different. Keep playing. Eventually the process becomes muscle memory. There will always be that stove load...or that split...or that day that switches things up on you, but with experience comes knowing what to do about it.

Sounds like your are ready to leave the nest...

 

[branchburner]

Nice to hear those results. I'd say with a little more experimenting and tweaking with wood selection and air control you will be running smoothly and virtually smoke-free with no problems. A warm stack means a clean stack, which is a pretty good feeling at the end of the burning season.

Different strokes for different folks (and stoves), but I now adjust my primary air and shut the stove back almost exclusively on the basis of flue temps rather than stove top temps. My flue gets real hot, real quick. And if the flue temp drops too low, I know the secondaries have stalled and I need to get the fire hotter, a fact that is not always immediately reflected by the temp of the stove itself. Ultimately, it is the low stack temp and not the stove temp that yields a good crop of creosote.

Happy burning!

 

[begreen]

This year I've found myself going more by flue temps too branchburner. Warming up from a cold start the stove top can be 250-300F, but the flue is approaching 6-800F. That is time to start shutting down the air. At that flue temp I usually will drop the air to 50-60%, wait 5-7 minutes, then close the air all the way down.

 

[Jags]

This year I've found myself going more by flue temps too branchburner. Warming up from a cold start the stove top can be 250-300F, but the flue is approaching 6-800F. That is time to start shutting down the air. At that flue temp I usually will drop the air to 50-60%, wait 5-7 minutes, then close the air all the way down.

I also base my cold startup adjustments on flue temps until the stove "catches up". This is the basis for my suggestion of two thermos if possible. One stovetop and one flue temp.

 

[jatoxico]

I have an insert so no flue temp readings for me but have been kicking around the idea of putting a digital temp thermo in the stream near the cap and monitoring effluent temps. Could make adjustments down below based on that. Anyone ever try this?

 

[FTG-05]

This year I've found myself going more by flue temps too branchburner. Warming up from a cold start the stove top can be 250-300F, but the flue is approaching 6-800F. That is time to start shutting down the air. At that flue temp I usually will drop the air to 50-60%, wait 5-7 minutes, then close the air all the way down.

How are you measuring flue temps?

I have double pipe inside the house (and in the chimney of course) so a magnetic temp gauge won't work on it. What do you guys recommend?

Thanks,

 

[begreen]

http://www.condar.com/Probe_Thermometers.html

 

[BradleyW]

I also like to use both the flue and stovetop temps when operating the stove. Last year I didn't use thermometers, only judged by the fire, and I wonder what mistakes I made. Mostly I think I ran the stove inefficiently and had a lot of heat going out the chimney that didn't have to.

 

[Woody Stover]

I'm just glad I've found a way to cleanly burn that cord and a half of pine I have sitting in the garage.Thanks for reading this epic post, and being so generous with your time and experience this past week.

Sounds like you're making good observations and getting a handle on it. I got here late, but with IR, PINE, POPLAR, SCRAPS etc, I saw the hot stove coming a few pages back. Several have commented that the IR likes to run, and with those loads... As mentioned, you'll get a feel for when to start cutting the air to keep the new load under control and avoid getting too much wood gassing. As also mentioned, about the time you think you have it figured out, you'll get the mystery load that goes high on ya, so be ready for that.

window next to the stove wide open throughout....Why did the draw get so awful with the poplar? (It is snowing with heavy-low clouds today, is it an atmospheric pressure issue exacerbating something else?).....Black smoke from the pine but not the poplar means there is something off with the pine?

Yes, atmospheric conditions can affect draw. And which window is open can make a difference (upwind or downwind.) I don't burn much Pine so don't know how a full load of smoke would look coming out the stack, but if I have a couple kindling in the stove, or a split on an outside fire, it's definitely making black smoke. But as you've seen, once the re-burn on the stove is working there's no need to worry about chimney deposits.

 

[wildcatbb]

I had a similar problem...3 weeks into heating with an old wood furnace. Chimney was plenty high, or so I thought, 4 foot higher than anything within 10 feet around it. Wood wasnt the best either. End result=Not good

 

[wildcatbb]

I had been fighting a bad draft and added 3 more feet of pipe after this pic was taken and the chimney was cleaned out and not a problem since!

 

[DougA]

I am speechless when I saw that photo.

I'm glad you got everything fixed. Amazing how a few feet will fix a drafting problem. I hope all those members who have been posting about bad drafts will read your post.

 

[wildcatbb]

It's quite amazing! My chimney was well within spec but I believe the surrounding woods on the north side and another roof line for my house to the southwest caused a weird air pattern. Everyone that looked at it before the 3' was added said it was fine"plenty of height "! Wrong.......as soon as I added that 3' the old smoke dragon ran like id never seen it do before!

 

[Sawset]

I have both a stove top and flue thermometer. I've found the stove top a very poor indicator, and the flue thermometer as the more critical indicator. The two can be completly independant of each other, where the flue to me determines limits and actions. I use three temperatures in the flue. Below 250 creosote condenses, at 550 creosote burns, 1000 is the limit of the duravent stainless chimney running continously. Below 250 I've had creosote condense inside the chimney and result in a puddle of black dripping out the back of the stove onto the hearth. At 550 condensation on the glass (and inside the chimney) will begin to burn back off and self clean. I've burned wet wood for extended periods successfully, as long as the temps are kept up. Cleaning the chimney afterward (once mid season, once at the end) produces only small amounts of carbon powder. Tel-Tru LT225R 200/1000degF is the thermometer I use. I recently had an issue with a plugged cap screen, and can now safely attribute the cause as 1) the stack thermometer was out of calibration by 100deg, it needs to be checked periodically, something I was lax on, 2) putting splits on in the middle of the night and walking away without opening up the air and getting the stack temp back up.

 

[Jags]

This past weekend I was cranking up a cooled down stove and hit 1100F probe temp. The stove top was at 400F.

This obviously called for an air adjustment, but if I was going by stove top alone I would have never guessed the pipe was ripping hot.

 

[branchburner]

This past weekend I was cranking up a cooled down stove and hit 1100F probe temp. The stove top was at 400F.

This obviously called for an air adjustment, but if I was going by stove top alone I would have never guessed the pipe was ripping hot.

I shudder to think how hot I must have sometimes run my flue before putting a thermometer on it, but sometimes I'd rather not see. Waiting for a downdraft stove to get to temp before closing the bypass can mean watching your flue get REAL hot, real fast. The spike on a hot reload is scary if that bypass stays open for more than a few minutes.

 

[Zemmie]

I have been reading through this post and thought I would through my two cents in. I have a Hearthstone Manchester installed last fall and am burning mixed hardwood and ash. One day I thought I would throw in a seasoned pine log for the fun of it and then went outside. Few minutes later black smoke, like I was burning oil. I know this stove very well now and knew something was wrong. Come to find out it was the sap on the bark burning off the log. So to conclude does the pine your burning have a lot of sap on it? If so this is definitely were your black smoke is coming from.

 

[DougA]

I shudder to think how hot I must have sometimes run my flue before putting a thermometer on it

++++1
I think many members here would rather not be enlightened. The 2 days before I discovered my baffle was broken, I was seeing flue temps that were way more than I would dare post here and they can jump from hot to holy sh*t in half a minute. It's crazy dangerous.

 

[DanCorcoran]

It's quite amazing! My chimney was well within spec but I believe the surrounding woods on the north side and another roof line for my house to the southwest caused a weird air pattern. Everyone that looked at it before the 3' was added said it was fine"plenty of height "! Wrong.......as soon as I added that 3' the old smoke dragon ran like id never seen it do before!

Please start a new thread with a title something like, "Look at this photo after 3 weeks with insufficient draft!". That way people who are researching draft problems can find it. You might also provide some background comments, as you did in this thread. Thanks for posting!

 

[wildcatbb]

Taken care of....new thread started!

 

[Jeffm1]

Ok, so here is the story.

Just got my first ever woodstove installed, Quadra-fire Isle Royale, with top-loading door.

It was installed professionally (though I'm really beginning to question if he deserves that title).

Stove is located in the basement, no outdoor air kit, drawing from inside the house. Flue damper also installed.

Pipe goes up through the main-floor, into our bedroom where it takes two elbows (approx 45 degrees each), to hit the roof at the proper angle to pass between the joists etc.

For 3 weeks burned more or less continuously. About half scrap 2x4s, and half seasoned pine.

Kept the damper at minimum, and played with the flue damper to a point where the flames were blue and dancing.

Did not allow it to smoulder to restart from the embers, but used paper and bark/kindling each time to restart. Then added scraps, then the pine.

After 3 weeks of pure wood-burning pleasure, without any issues or concerns, there was a strong smell of burning-plastic in the main-floor bedroom. Then shortly after a strong smell of woodsmoke. Then the 2" insulated pipe was too hot to leave my hand on. THEN there was a dramatic decrease in draw in the stove. Carbon monoxide detector went off, reading of 89 PPM in the bedroom.

Contacted the installer, and we tried to light it again (a few days later). No-go. No draw at all. Took the flue damper off and put a straight pipe in instead. No-go, still no draw. Went up on the roof, and the cap itself was totally, completely plugged with creosote. Taking the cap off allowed us to get a fire going, but the draw was still terrible. No smoke or carbon monoxide exited into the bedroom during this fire.

Installer says it is an issue of negative pressure in the basement (our furnace also draws straight from inside the house). Says this has slowed down the ascent of the smoke, to the point that it is cooling and condensing on the pipe.

During the 3 weeks of burning, draw was never a problem. Never had smoke pouring out of the stove, trouble lighting etc.

Installer also says a major factor is the humidity in our house (+/- 45%, down to 35% after running the stove).

And the "punky" wood we have. I'm familiar with this term, and to my mind our wood is absolutely not punky. My brother has been burning from the same batch since September and has had no complaints. It is totally dry, well-seasoned for at least a year. The installer does not contest any moisture issue with the wood, but he says it has "lost all of its energy" and that some of it was cut from dead trees: "never ,ever burn deadfall".) I think he may be trying to shift the blame onto us to cover his butt.

I don't doubt that the negative pressure is part of the problem here, but my real question is: to your mind, does this explain how we somehow managed to completely clog our chimney with creosote in a matter of 3 weeks?!

Seems to me something in this system was grossly miscalculated. When originally purchasing the stove, sales rep said we would essentially never have to clean the chimney, because the stove burnt so clean. Install guy had said we should have it done once per year. I work from home and was at that fire every 1.5 hours having a great time with my new stove, tweaking and tuning the flue damper, keeping the flames blue and rolling: was this the issue?

Even the flue damper was covered in creosote. How is this possible in THREE WEEKS?!

Thoughts? Insight?

Will provide further details if helpful.


Thanks.

New burner here and I will admit I only read three pages of this long thread so forgive me if someone already mentioned this. But the flue damper seemed to jump out at me as well as this next point. Do you live in a spot that has high winds at times? I live in a place that gets extremely windy for three months out of the year. One night when the wind was really kicking up and swirling we had a draft coming back own the stove pipe and smoke smell in the house. If you live near a hill or edge of forest or other obstacles sometimes these create different pressures that Jack with the draft up your chimney. You said your stove was running great and then all of a sudden whammo . Plugged up. All the other points have already been mentioned but I did not see anything about high wind issues. I am wondering if high wind sessions combined with the stove in your basement was the problem. If that could be an issue just replace your standard chimney cap with a wind cap and the problem will be solved. Also something else that would go long with this...maybe your chimney needs to be taller. If it sits in a bowl it might be fine when the wind doesn't blow hard but when it does all the pressures change causing back pressure in your flue. I would look at this as well, especially if the top of your chimney is below the line of the peak of your roof.