Thread: Black goo dripping down my stove pipe

Hey ... I'm new to this forum -- never heated with wood before this winter.

I just bought a log home here in Montana with a "Blaze King" woodstove in the basement. When I first started using the stove this winter, it wouldn't smoke at all ... had a great draw. I could open the door to put in more wood and no smoke came out.

This is an air-tight stove with a built in catalyst (probably old), and an air control knob, plus the two blowers.

After a while, it got more and more smokey. Now, it's starting to drip black goo down the stove pipe.

One more piece of info ... here in Montana, we only have softwoods; fir, pine and larch.

So ... obviously I need to clean the inside of the pipe ... how can I do that? If I brush it down from the roof, how can I get past the butterfly valve in the flue (just above the stove)?

Also ... do you think that the goo buildup in the pipe is causing the stove to not draw well?

How can I make it draw better? Should I run it with the flue damper all the way open and rely on the air control knob? That's what I've been doing. Or should I damp the flue a bit also?

Thanks!!

Here are some pics:




Thanks for any help you can provide.

Do you have an 'air-tight' stove or an antique? Air-tights should not have that "butterfly" (proper term is 'damper') as the stove controls take care of all draft adjustment. I suspect the damper is one of the causes of the 'goo' - it for sure is if you are running the stove with that damper mostly closed.

The 'goo' is creosote. Your chimney needs a good cleaning to start with and you need to burn hotter fires AFTER you clean the chimney. How to clean past the damper? Remove it and then reinstall is the only reasonable way.

The 'goo' should not be dripping down the outside of the pipe. It belongs on the inside. Your chimney pipe is installed upside down. That is understandable as, for some reason, that is way it will naturally install if you don't correct it. In my installation I had to have the local grange make me a pipe section with the crimps on both ends to get the pipe going right. It should be installed with the crimped end sticking down inside the joint below it.

Harry K

damn man, thats a lot of creosote inside the pipe if its dripping that much. i would NOT light another fire until the pipes have been cleaned, inspected by a 'sweep and then (and only then) i would burn a hot fire, maybe some seasoned birch.

Don't bother getting it inspected by a sweep or cleaned. You already know what he's going to say. The same thing Harry said. You're pipes are installed backwards. Lose the damper like Harry said.

I'd yank the whole thing out and replace it with 18 gauge stainless. Stainless because it will take the heat better than steel. Don't burn it the way it is, it's a nice way to start a fire inside your house, or at least stink it up real good.

Originally my stovepipe was installed like yours. I redid it in stainless 10 years ago and have not had any issues with it since. Where it comes out of the stove, you'll need a double ended female pipe since the pipe has to slip over the stove outlet. It will still have a tendency to leak creosote there. What I did was use a 1" wide section of flatbar and welded tabs on it to make a band clamp. I wrap a piece of welding wire around the pipe at the stove and put the band clamp on it and tighten it down. It puts a crimp in the pipe against the stove outlet and forms a near perfect seal. It has never leaked.

Ok ... thanks for the info. I'm going to have to stick with the same black single-wall pipe for now because the SS stuff is so expensive. I'll clean it first, then take it apart and re-install it properly.

Next questions:

1.) Can I use a wire brush on ordinary steel pipe?

2.) Anybody ever replaced a catalytic combustor on a Blaze King before? What do they cost?

Thanks!

OMG......My guess is the only reason you have not had a chimney fire is because you have not had a single HOT Fire. How long is your run of chimney? Is all pipe above the floor/ceiling double wall Class A pipe? Once it passes outside your home. How long is the run and is it inside a chimney chase?

PS. DO NOT LITE THAT STOVE UNTIL YOU PROPERLY CLEAN ALL PIPE.

Originally Posted by WoodTick007

OMG......My guess is the only reason you have not had a chimney fire is because you have not had a single HOT Fire. How long is your run of chimney? Is all pipe above the floor/ceiling double wall Class A pipe? Once it passes outside your home. How long is the run and is it inside a chimney chase?

PS. DO NOT LITE THAT STOVE UNTIL YOU PROPERLY CLEAN ALL PIPE.

Hey ... thanks for answering ... I'm going to fix everything today. I just bought this house, and I'm guessing the pipe hasn't been cleaned in a long time.

To answer your questions, 2 weeks ago, I had a very very hot fire ... thermostat was up around 1200 degrees. And during that, I think I might have had a minor chimney fire. There was noise inside the pipes and even the 3-wall pipe was hot to the touch.

The pipe from the stove in the basement to the floor of the living room above is 5 feet of single-wall 8" pipe. Above the living room floor it is 3-wall black steel pipe. Then it goes another 11.5 feet up through a cathedral ceiling, then outside another 5 feet above the roof. Total length is about 24 feet including junction boxes.

I guess we've been lucky. The roof shingles are made of concrete, so that's a big plus for fire safety.

- Is it okay to use a wire brush on black metal pipe? Or do I have to use a plastic brush?

- Can a creosote buildup in the pipe reduce the draw of the chimney?

Thanks for all your help!

Originally Posted by MontanaMan

Hey ... thanks for answering ... I'm going to fix everything today. I just bought this house, and I'm guessing the pipe hasn't been cleaned in a long time.

To answer your questions, 2 weeks ago, I had a very very hot fire ... thermostat was up around 1200 degrees. And during that, I think I might have had a minor chimney fire. There was noise inside the pipes and even the 3-wall pipe was hot to the touch.

The pipe from the stove in the basement to the floor of the living room above is 5 feet of single-wall 8" pipe. Above the living room floor it is 3-wall black steel pipe. Then it goes another 11.5 feet up through a cathedral ceiling, then outside another 5 feet above the roof. Total length is about 24 feet including junction boxes.

I guess we've been lucky. The roof shingles are made of concrete, so that's a big plus for fire safety.

- Is it okay to use a wire brush on black metal pipe? Or do I have to use a plastic brush?

- Can a creosote buildup in the pipe reduce the draw of the chimney?

Thanks for all your help!

Ok to use steel brush on steel pipe. Creosote buildup can decrease the draw as it decreases the diameter of the pipe.

Now the important stuff. If you had your stove up to 1200 degrees with steel pipe, you were asking for trouble. At those temperatures and with the stovepipe that hot, you risk collapsing the pipe due to the hot steel and the vacuum of the increased draw. It may already be deformed, check it closely. With a steel pipe, I would not let the cresote buildup happen over any period of time. Burn it at 500 every day or two for an hour. The idea is to burn the creosote out before there is alot of it.

The reason I recommend stainless is because it can tolerate a chimney fire much better than steel.

It would take one h*** of a lot of creosote to decrease the draw significantly. I would be inspecting the cat converter for blockage as the likely suspect.

Another suspect is the chimney cap. In the middle of a cold night last winter my smoked/co alarm went off. I had been having draft problems. Prior year I contracted to replace the roof which also resulted in a new cap for my tripple wall. Inspection the next morning showed that the new cap had a screen in it (probably to keep birds out). That screen was clogged with fuzzy dry soot. Tin snips fixed that in short order! Than god for CO detectors!!!

Harry K

To answer your questions, 2 weeks ago, I had a very very hot fire ... thermostat was up around 1200 degrees. And during that, I think I might have had a minor chimney fire. There was noise inside the pipes and even the 3-wall pipe was hot to the touch.


Definately hot enough to buckle that pipe. And you say it is now not drafting as well as before. One reason is well documented here already, build up of creosote. The other is if a pipe/ pipes/ joints are buckled at all, you would now have an air leak where you don't want it. The damper in the pipe is doing the same thing, leaking air around the shafts. Both of those will cool the chimney. The noise you heard was a chimney fire and a brutally hard draft as it was searching for air. If you had gone outside and looked at your chimney, you may well have seen flames coming out of it. You want an air tight chimney, no damper, hot fire / exhaust pipe, 400~500 deg, NOT 1200deg. , control from the furnace. Clean it, get the parts right and tight , then marry that thing until you are sure you have it under control. Ask me how I know some of this!!!!!

Another suspect is the chimney cap. That screen was clogged with fuzzy dry soot. Tin snips fixed that in short order! Than god for CO detectors!!!

Harry K[/QUOTE]


Ive had similar problems with my spark arrestor screen. I just climb up there and tap the screen with the wire brush and the stuff falls off. Ive thought about removing the screen but was concerned about the spark arrestor function of the screen. i've seen glowing embers of cardboard or paper after the fire was lit caught in the screen.

Also read somewhere that the glues and resins of some cardboard can collect and clog parts of the stove and chimney? is this true and is this an issue?? And what brushes are reccomended for use in Stainless triple wall chimney pipe? says right in the installation instructions not to scratch during cleaning.

If i were you I would just replace the pipe instead of trying to clean it. The single wall black pipe isn't that costly.

One reason creosote forms like that is the pipe is not hot enough to allow the gases to escape and then the gases turn into the black goo you have going there. I think you should replace the pipe and then make sure your fire is hotter in the future. Alot of people will damper down their fire so much at might trying to acheive an overnight burn that the gases are not hot enough and the result is black dangerous goo.

Also, your local stove shop should have a powerdy product that you sprinkle on your fire that will help control creosote. Just mt .02 cents.

I agree with Harry K.
We have a kiln which dries firewood. Before we learned to clean it before every firing we found it almost completely clogged shut with creosote. Also, if the cap on top of the pipe is open, rain will run down the chimney and appear black also. Chimney brushes come in different sizes. If your chimney is pop-riveted you may wish to drill through the rivets so you can clean the pipe on a regular basis otherwise this situation will occur again. We use dry wood and still accumulate creosote. Too much smoke is an indication the damper is closed or the chimney is clogged. You may wish to remove the damper altogether.

Another add on thought. All joints in single wall pipe should be secured with at least 2 sheemetal screws. A chimney fire is bad news but if the draft tears the pipe stack apart...and there are reports of that happening.

I toss a big chunk on the stove when I go to bed and shut the air down. Still has wood and enough embers in themorning to get it going. Never have had the black runny goo. I clean my chimney once at the start of the season and all it get is about 1 gallon of powdery grey/black soot.

Harry K

You are lucky to get the kind of advice from experience here.....it's all crucial for you.

With that kind of flammable creosote you got, do not burn that stove. Step away from the stove.

1. Get SS pipe to replace what's there now. SS is pricy, but it is easier to clean and lasts much longer than any other stovepipe, since the junk from incomplete burns won't bond to SS. With that kind of creosote you couldn't clean it all anyhow. Get stove brushes for your NEW pipe.

2. Listen to these guys: install the pipe right so the creosote will go INTO the stove and burn up. Male end down. And, use three screws/pipe joint.
The SS is hard stuff to drill piolt holes so get some new drill bits since they break too often

3. Catalysts work IF they're used the right way. Yours is probably dead. Pull it out and get a new one. Google for suppliers or try -- SCPRTOTOTECH.COM -- or your local stove shop.
This is why the stove makers went to non-cats: customers did not use them the right way or maintain them at all. It does take some (little) care to burn cat stoves. They are more efficient than most of the non-cats.

4. Make sure your homeowner's insurance is up to date.

Good luck.