Dreaded creosote in my stovepipe ONLY?

[brider]

I burned all last winter for the first time in a new Oakwood stove, all hardwood. Granted, there was a learning curve and I started burning fires waaay to "cold", but by New Year's I pretty much figured it out...

I allowed the stove to jack up to 600 (stovetop thermo) probably every day, and occasionally it would crank to over 700 before I could close it back down, but these were only temporary, and my wife and I could usually get it to simmer between 400-550.

There WAS a time, however, when I ran out of wood in late Feb or early March, where we burned a fair amount of green oak which naturally didn't like to start, OR burn very hot...

So last weekend a wren came down my chimney and got trapped in the stove itself, and to get it out I removed the single-wall stovepipe from the stove collar to the double-wall ceiling/roof connector.

The stovepipe had a VERY thick, flaky layer of creosote, while the double-wall chimney pipe was VERY clean!

Does this sound typical? I would have guessed just the opposite, that the single-wall pipe inside the house would have been clean (closer to the fire, not in contact with outside cold temps), while the outside double-wall would have had the creosote buildup.

What should I do to minimize this inside-the-house creosote buildup, short of burning higher temps, and making sure I don't burn anymore green wood?

 

[BrotherBart]

Everybody has opinions and all I can tell ya is my experience with the same thing. The same thing used to happen to me with the stove in the basement office with the single wall connector pipe. After I started starting the fires with the top down method using paper knots on top it hasn't happened since. Seems the fast burning, creosote free, paper heats the single wall pipe fast and so the crud doesn't collect on it like it does with slow bottom up start-up fires into a cold pipe.

Everyone's mileage many vary.

 

[SmokeyStover]

What you described is quite normal and easily explanable. Creosote forms on the walls of stove pipe and chimneys through the process of condensation. Hot gasses hitting a cool surface yields creosote. The single wall pipe radiates heat easily and therefore presents a cooler surface. The chimney is insulated which keeps the heat in and the surface warmer. The moisture will condense on the cooler surface first and load up your pipe before it gets to the warmer surface of the chimney. It's same situation where the chimney may be very clean but the chimney cap is loaded with creosote.

 

[brider]

Sooo..., the double-wall connector pipe would have reduced or eliminated this problem? At the time I was scrambling to find connector pipe to finish my stove install, the double-wall version was too expensive, so I went for cheaper (but not by much!) 22-ga single-wall pipe.

I guess I'll just suck it up and take down the connector pipe after every season and clean it out.

The wren did a GREAT job, BTW, she was fluttering inside the connector trying to get up the 16' chimney to the cap and out, and almost polished the inside of the pipe in a small area.

 

[Highbeam]

Yes, double wall would have reduced the problem. Even though the chimney is exposed to outside air temps vs. the single wall seeing inside air temps that is only a difference of 50 degrees and teh insulative properties of the chimney pipe easily add that much to the chimney. The temp on the inside of the flue wall is what matters and it will be much colder on that single wall section.

I'm assuming you have some 90 degree bends in your chimney system which eliminate the possibility of simply running the chimney brush from the cap to the stove? If you could get a straight shot between the cap and stove then you never need to disassemble the stove pipe to clean.

Oh and while the single wall that you chose was cheaper to install, it has a limited life and must be replaced much much sooner than the double wall which is stainless steel on the inside.

 

[Todd]

Try sealing your stove pipe connections with furnace cement. You may have some small gaps in there sucking cooler air into the exhaust creating creosote.

 

[brider]

I remember agonizing over double-wall (which I wanted) vs single-wall. I ordered the double-wall assembly, but it was missing a critical connection adapter, it was mid-October, I would have to get a big $$ replacement from another source, bla, bla, so I found a stove shop in Maine that sold locally produced heavy-duty 22-ga pipe and used that instead. I believe that your run-of-the-mill SG pipe is 24-ga.

My pipe IS heavy and stiff, so I'm sure I'll get many seasons out of it.

The good thing is the connector is a breeze to remove and clean.

The entire chimney is a straight shot 16' straight up. But coming down from the top with a pipe brush is impossible, to my dismay; the roof pitch is too steep for me to get a brush down from the top, and removing the top section of chimney is too scary. I will have to go UP with the brush.

 

[Todd]

Try sealing your stove pipe connections with furnace cement. You may have some small gaps in there sucking cooler air into the exhaust creating creosote.

creosote is not created, its the result of unburnt pyrogas

And when those unburnt hot pyrogases pass by a leaky pipe seam they rapidly cool creating creosote.