Black crust all over ground/cars this am - anything to worry about?

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TheBaron

Member
Dec 27, 2012
93
Eastern ON, Canada
We were burning over the weekend for about 24-36 hours straight, went through about 5 reload cycles on the Jotul C450 (non-cat stove). Temps were never over 600 and kept in the sweet spot most of the time. On reload had some strong flame action as usual before shutting down the air, but nothing to be concerned of from past fires.

This morning went outside and there are black chunks/flakes directly beside the chimney on the ground and on the cars. Cap seems ok/normal based on my observations from below and compared to before.

Is this normal that sometimes a 'crust' gets released from a chimney or cap, or is this something I should be concerned about (sure sign of a chimney fire?). Looking for thoughts on what this might be and actions to take (if any).

Appreciate the thoughts/advice.
 

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How long is your wood seasoned (split and stacked off the ground) generally?
 
Something violent happened in that chimney. I can't see even strong winds cleaning that out of the cap. I'm guessing a fire while you slept or else a small one that you didn't hear.

In addition to gzecc's question, when was the last time the chimney was swept?

Are you measuring chimney or stove top temperature? How hot are you letting things get before beginning to close the air down in stages presumably? Or do you close the air down to a cruise setting all at one time?

pen
 
You have red oak in your signature, that is one of the longest to season woods out there, nice BTU's once it has seasoned for 3+ years, what is the moisture content of what your burning?

Generally the only time you get creosote bits blown out like that is when you have a chimney fire, the upwards vacuum that is formed will heave out chunks of creosote everywhere.

600 on the top middle is cooking pretty good, the problem might be you are shutting down the air to much and it is smoking more than it should towards the end of the burn.
 
How long is your wood seasoned (split and stacked off the ground) generally?

I buy the wood 'seasoned' from a local respected wood supplier. He claims the wood was seasoned for at least 2 years. I tend to believe him as the wood lights easily and never hisses. Need to get a moisture meter, that was on my Christmas list but didn't arrive as planned.

Something violent happened in that chimney. I can't see even strong winds cleaning that out of the cap. I'm guessing a fire while you slept or else a small one that you didn't hear.

In addition to gzecc's question, when was the last time the chimney was swept?

Are you measuring chimney or stove top temperature? How hot are you letting things get before beginning to close the air down in stages presumably? Or do you close the air down to a cruise setting all at one time?

Chimney was swept last year at the end of the burning season, since then I have had about 1 face cord through the stove. I bought the condar stove-top thermometer and put it in the gap at the front center of the stove (insert). I also have an IR thermometer that I hit the various spots with through the 'gap' between the stove and the surround, it is typically around 575-625 as a max range.

I typically let the wood get going for about 15-20 minutes with a few small pieces of fatwood and 3-4 smaller splits on top. I shut the air down to about half then wait another while (45-60 min) before closing it down more (1/4) if it is above 500 and cruising. Typically the secondaries are going at this point and are enhanced/more obvious.
 
The process doesn't sound bad, but what surprises me is that it takes 45-60 minutes for things to be 500 and bring the air down to a cruise. With a load like that, I wouldn't expect it to take that long if the wood is really seasoned.

Sounds like the wood is partially seasoned, but not all the way there. Hissing is a tell-tale, but you may still have wood that isn't quite ready even without it.

Unless the chimney temps are spiking before you start closing the air down, something here doesn't add up.

In general, you would be by far the exception, and not the rule, if that wood has been cut, split, and stacked for 2 years when coming to you from the seller. As was mentioned by mellow, even if the seller did do that, it just might not be enough time for that fuel.

In general, I'd really recommend getting a plan together to get more wood on hand and ensure the seasoning is truly complete by doing it yourself.

In the meantime, I'd highly suggest inspecting that chimney and preferably sweeping, before continuing as something happened here.

pen
 
Is this a freestanding stove? Or is it an insert / installed in a fireplace?

Have you checked to make sure there is a cap on the bottom of the cleanout if there is one? Or if the liner is directly connected to the stove, have you checked to make sure the connection hasn't slipped and is letting air in? If either were to happen, you'd have accelerated creosote formation even with decent burning practices since the cold air getting sucked into the flue would cool the exhaust gasses down.

pen
 
I've seen that growing up....my fathers version of "seasoned wood" was cutting in the fall (standing dead) and splitting before winter. Needless to say, in the old smoke dragon, creosote build up was fairly common. We had one small chimney fire and I remember seeing all types of black soot on the snow covered ground.

I would check your chimney ASAP and get yourself some seasoned wood. In my fathers case, he has since moved to burning pellets so those days are long gone thankfully.
 
Is this a freestanding stove? Or is it an insert / installed in a fireplace?

Have you checked to make sure there is a cap on the bottom of the cleanout if there is one? Or if the liner is directly connected to the stove, have you checked to make sure the connection hasn't slipped and is letting air in? If either were to happen, you'd have accelerated creosote formation even with decent burning practices since the cold air getting sucked into the flue would cool the exhaust gasses down.

Thanks Pen,

This is an insert, professionally installed in a fireplace, with a stainless liner installed from top to bottom (single wall is all that would fit in the flue tile according to the installer.

I removed the baffle (heavy) about 3 weeks ago and looked up the chimney to inspect. There was approx 1C of black granules (just like I saw outside this morning) that had collected on top of the baffle that I cleaned out. Looking up the chimney from the inside things looked pretty clear, but that would change I suspect the further up the chimney we go given it is external and only a single wall ss flex liner.

My estimates of time for the different steps are fairly approximate. In general things seem to start going pretty well and there have been a few times where I feel that the initial start got going a bit crazy before I shut the air down. I didn't think anything of it at the time as my stovetop was still around 300 or so. I wish I could get a chimney thermo but there really isn't anywhere I could put it and still be able to see it.

I'm going to stop burning now and do a thorough inspection by a qualified person locally. Chimney is about 25' long so hard to get up there myself to do the inspection at this time of year. Will also build a proper woodshed so I can store more wood on-site (I'm in the City), but this will take me till mid-summer 2014. I recognize and have always agreed with the benefits of seasoning it myself.
 
Sounds like the evidence of a classic chimney fire, to me.
 
I can't see your cap too clearly in the photo to tell if you have a screen in it or not? It looks pretty black, at any rate. With that much creosote on the ground I would make sure you don't have any leaves trapped up against your chimney at the base. You know you have stuff coming out of the stove and making it to the ground, so you definitely don't want any embers dropping down right next to the chimney and landing on some old leaves or other debris that could be up there.
 
The stuff collects on my top plate as it falls off of the cap. I figure a strong wind would blow it off to the ground like that.
 
The stuff collects on my top plate as it falls off of the cap. I figure a strong wind would blow it off to the ground like that.

That's what I was hoping it was when I first saw the stuff on the ground. It isn't the first time either (saw the black flakes/granules once before about 2 weeks ago). Was hoping it was some 'minor' creosote buildup from my cap that was coming loose and falling to the ground (it was very very windy last night, I got woken by a gust at one point). Could also be a sign that some of my overnight fires were smoldering a bit and my buildup is accelerated compared to where it should be after the last cleaning.

Either way, given the feedback here (and my own common sense!) I will have to get it inspected / cleaned before burning again.
 
It sure won't hurt to have it thoroughly inspected but I've had a little of the same stuff in my yard after a really windy day. It only happened when it was high winds and when I go to my roof to inspect the cap there's usually a little bit of the stuff that falls off like Brother Bart says.
 
Certainly get it inspected, but I tend to agree with Brother Bart, its stuff blown down from the cap.

Hard to imagine you would have a chimney fire after burning only 1 face cord of wood.
 
Not to play Devils advocate or by any means condone unsafe burning practices but with the right weather/wind and fresh snow a little black crud can look a lot worse than it is.

You can get what looks like a lot with different scenarios such as: intermittent burning(non-24/7 for weeks on end) then a hot fire sucking crud up and decent wind distributing it about.

I get some evidence of this from time to time and know there was no Chimney fire creating it.

A little inspection after your weekend fun and a quick run of the brush would give me more piece of mind - especially if you are not absolutely sure of wood MC and comfortable with what is going on in there.
 
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A little inspection after your weekend fun and a quick run of the brush would give me more piece of mind - especially if you are not absolutely sure of wood MC and comfortable with what is going on in there.

Exactly, like I said before, something isn't adding up. However, whenever something is seen that is amiss, an inspection and cleaning is wise. If the OP is able to pull the baffle and look up this thing, that is about 75% of the way to getting a cleaning done with something simple like a soot-eater. The only other things required are a very bright light to be able to see and do a good inspection and a drill to run the soot eater.

The only time I've ever had black out in the yard or on the roof is after having a small chimney fire. In inspecting the black, I was able to find a few pieces that looked like popcorn or black Corn Pops cereal. Puffed up creosote like that is often a sign of things getting real hot.

I hope it is something simple like just the right conditions for a bunch of powder to blow off all at once (and considering it is only a face cord of wood burned it probable is), but I still think it's wise to be certain of that before proceeding.

pen
 
might have been something the neighbors were doing... ever see a leafblower cleanout?
 
Will do a more thorough look up the chimney tonight if I can get the baffle out without removing all of the firebricks (would hate to crack one). Stove is fairly new and still getting used to it but feeling pretty comfortable.

This residue is definitely coming from my chimney, and not an external source - but wishful thinking! :)
 
I have had black flakes several times in my couple years of burning with the non cat. My flakes are not crusty but turn to dust when you rub them in your fingers. I just had some a couple weeks ago and have since then swept the pipe and there was definately not a large build up. I think it's just a light buildup that can happen near the top of the pipe where it's the coolest and then with a strong wind it gets taken away. But a cleaning gives peace of mind.
 
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Not to derail, but is that real brick on the gable and your chimney? Is it a class A in there with a façade? Looks nice.

TS
 
Baffle on the 450 comes out easy, just remember to push back and up then lift up right side then take it to the top right corner and down and out, just do the opposite to get it back in.

I thought it was going to be more complicated than that from reading on here but it wasn't that hard.

No bricks are needed to be removed.
 
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Any chance that you were recently burning newspaper or cardboard in the stove?
 
Not to derail, but is that real brick on the gable and your chimney? Is it a class A in there with a façade? Looks nice.

TS

Old house so brick was more common (lots of clay everywhere within 100km). 1929/1930 approx.

There are a few dormers in the 1 1/2 storey and we recently redid those with Hardie.

Chimney was re-bricked from the roof line up a few years ago due to deterioration.
 
Any chance that you were recently burning newspaper or cardboard in the stove?

Good question. Over the holidays there was some cardboard burned, nothing substantial knowing it wasn't good to do this (like coated papers, etc). That was a good 3 weeks ago now, not recently.

There really seems to be a lot of the crud around, especially on the roof in the snow. Tried rubbing it between my fingers and it quickly turns to dust. No larger 'corn puffs' or crunchy pieces noted.
 
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