corey wrote:I'm just confused I've never had this brownish liquid. My chimney was in good shape last week when I clean it. It just like the coal soot has a little water in it.
For what it's worth; I primarily burn KY bit (some anthracite but NEVER wood. My chimney is an old unlined brick chimney). I also have a strong draft. I have six feet of 8" flue pipe connecting my stove to the chimney that has a baro damper and a oil furnace flue in line before it gets to the chimney.
This will be my 3rd year burning coal and I have never had anything that would even resemble tary liquid in my flue pipe.
My flue pipe and chimney will get a layer of soot build up in it that will fluctuate from about 1/2" to 3/4" thick throughout the season. Once that layer is established it will run like that all season (my season is only about 4 months).
I've checked the house chimney each season and have never had to even clean it. I run a brush thru the metal flue pipe when I disconnect at the end of the season. Then when I start with a clean pipe, It will usually take a couple of weeks for it to build up that layer. I just pull the cap off of the end of my flue pipe (I have a tee at the stove end with a cap on it) about once a month just to check it.
With all that said, my guess is you have a thin layer of hard creosote that was existing in your chimney from wood burning that is causing your issue. Maybe the soot from the bit is reacting with it somehow causing it to melt.
The biggest thing that I do when burning bit is when I reload, I make sure I have hot hot coals. I actually do pull most of the hot coals forward and leave a thin layer in the rear. I usually bank to the rear of my stove. I open my secondary air all the way up for 20 to 30 minutes to burn off the releasing volatile gasses (by doing this I get very little smoke). Then as the stove starts to heat up I begin backing the secondary air down. But, I NEVER close off all of the secondary air to bit coal. If I want to slow the burn down more, I open the baro up as much as needed and run just a sliver of primary air.
In my experience, KY bit burns much like wood. It doesn't really need primary air for long normal burns. Primary air just burns up the coal faster and makes the stove run hotter.