Checked my chimney today, but how much creosote is too much?

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mbk2000

New Member
Nov 24, 2007
43
Coastal Maine
Well, the subject line pretty much says it. I've been burning 24/7 for 3 weeks. Looking up from the access door in the basement, I can see all the way to the opening with some crusty areas about halfway up, on two or three sides of the liner. Good, bad? I have no idea. Help please. :)
 
I forgot to add that I had the chimney swept just before firing up the stove for the first time so any buildup is going to be recent.
 
Most sweeps recommend a cleaning with more than 1/4" of creosote build up anywhere in your system.
 
Is the accumulation occurring shortly after the stove pipe enters the flue? Any possibility of posting a photo?

Also, is the access door gasketed? If it's leaky, it can be cooling down the flue gases and increasing creosote accumulation.
 
1/4" that far up seems like it would not even be visible. So the fact that I can clearly see the creosote is bad then? The majority of the chimney appears clean except for this mid portion. Is this dangerous now?
 
BeGreen said:
Is the accumulation occurring shortly after the stove pipe enters the flue? Any possibility of posting a photo?

Also, is the access door gasketed? If it's leaky, it can be cooling down the flue gases and increasing creosote accumulation.

I'm looking at it from the floor of the basement but, yes, it does seem to be in that area just where the pipe enters the flue. I'll try again to get a decent picture of it. The door is gasketed and seems intact with a good seal. My wood has been not so dry but I am careful to burn hot enough fires and my overnight burn never leaves any black on the window or bricks so I'm surprised to see that buildup. That's why I have to ask. I have no idea if it's normal or bad.
 
Did you sweep it yourself? Maybe you missed that spot? For peace of mind I'd run a brush down just to see what I had. Typically the gooey black tar stuff is the most dangerous.
 
It's too far up the flue for my flash. There were two old flue holes (I don't know the technical name) that were covered over on the first floor with brick and concrete like the patch over just to the bottom right of the photo. Could that be what I'm seeing? It all looks black from the bottom so I can't tell. Having never looked up a chimney before, I don't know what real creosote buildup might look like. Anyone have any pictures of that? Geesh, I'm such a newb.

 
It looks like you have some black, shiny creosote showing on the left side of the photo. Looks like it has even dripped, globed down in the lower left hand corner. That type of creosote is tough to remove. I can't estimate when it built up (and that is your real question). It could have been there prior to having your chimney swept. A normal sweeping won't do much to remove this type of creosote. The gray, flakey type of creosote (similar to a marshmallow roasted/burned over an open fire) will brush down easily. What to do? Safest thing to do is try to sweep it yourself and then inspect and compare. I would think that type of creosote continues up the rest of the chimney as well. How about calling the sweep who first cleaned it and tell him of your findings. Maybe he would stop by and do a visual from the area where you got your photo.
 
I don't want to jump to conclusions. Can you describe what is in the picture? Is the picture looking up the chimney from the basement access door? Is that shiny object just barely discernible the stainless flue pipe entering from the stove? And is the majority of what is visible no longer used or is there a basement stove as well?

I've lightened up the shadows a bit so the dark area is easier to see. It's hard to tell, but it does looks a bit dirty up there.
 

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A good safe rule of thumb...at least in my household....when in doubt, sweep it out. If you are not confident that it's clean just sweep it.
 
BeGreen said:
I don't want to jump to conclusions. Can you describe what is in the picture? Is the picture looking up the chimney from the basement access door? Is that shiny object just barely discernible the stainless flue pipe entering from the stove? And is the majority of what is visible no longer used or is there a basement stove as well?

I've lightened up the shadows a bit so the dark area is easier to see. It's hard to tell, but it does looks a bit dirty up there.

That is looking up from the bottom of the chimney. The stainless pipe would be from my wood stove. This flue had a oil furnace AND a wood/coal boiler hooked to it recently in the basement. Plus the two openings on the first floor which are now patched. The lower concrete patch that you see is from that wood boiler so I'm thinking that is where the lower slick creosote came from. I disconnected the oil furnace from that flue so none of that is used now. The previous owners left behind a brush so I guess I'd better learn how to sweep. I'm not liking the idea of climbing on an icy roof. This is not a happy activity for a native Floridian. I don't have any idea what to do when I get up there anyway.
 
OK, that is what it looked like, just wanted to be sure. You did the right thing by sealing off old ports and removing the furnace from the stack. If you can get a powerful flashlight to shine up there you may be able to see more. Try a Mag light or a 6v lantern in the daytime. Use a mirror if necessary to look up to the cap.

I like woodconvert's saying (Did Johnny Cochran write this?)When in doubt, clean it out. If it's getting at all black and wooly above the entrance of the stainless pipe, time to brush.
 
Actually it looks like you can sweep the flue from down the basement. With fiberglass rods and the proper brush you may save yourself a trip to the ER.

Good luck!
 
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