Build-Up in the Chimney?

Over the past couple of days I've noticed that the manometer was reading lower than usual. Now, granted it has been pretty warm but I became fully concerned yesterday when at 37* my draft on the manometer was reading only .02" WC; I have to add that I've been running the stove at 290* at 47* usually and had the temp bumped to 400* and still saw a low draft yesterday.

I had last week cleaned out the horizontal run coming from the back of the DS until there was nothing left in it. So, per directions from Coalfire when I went home last night I re-cleaned the horizontal run I noticed the draft increased to .04" WC. And again, per Coalfire I climbed up on top of my roof and pulled the chimney cap off to make sure my liner was not collapsing in on itself. All is well with the liner.

I do however notice a build-up of ash on the inside of the liner itself. Remember, I have a 316/Ti SS liner (flexible) and I see that the ash is building up on the inner walls. I also noticed that aside from stalagtites coming off of my chimney cap the ash is building up on it too.

I know the answer to my question is going to be yes. But I'll ask anyway. Could this slight build-up of ash accumulating on the inner walls of my liner and on the inside of my cap be cause for my low draft condition? It's a 6" liner runs the full 18' of my chimney.

Since I know the answer is yes. Can I safely clean the chimney with the stove running or do I need to shut-down? I only ask because if I shut-down now at this point in the season is there really any point to starting back-up? I could just as easily run my furnace for the next few weeks (shutter ) or find some wood to burn.

I was thinking a 4" brush and run it down the chimney to knock off some of the built up ash. I figure 4" because it won't completely block the escaping gasses. And it'll only take about 10 minutes.

I'm sure I'm going to catch some flack for even contemplating cleaning the chimney with the stove running but I'd like to avoid a shut-down until it's officially time.

Your draft will go down when it get warm outside. Mine will go down to .02 when idling.

Depending on the type of chimney, if you cleaned out all horizontal runs, there should not be much buildup on the vertical pieces....

You can try and clean it out while running if you can get to it. Just because of the ash going up in your face with the draft.

Yeah, I know the draft will go down this time of year. Several weeks ago it was 70* and my draft never went below .03" but this week with temps hovering around 50* so far my draft has dipped below that. But, then again, I still had the stove hovering around 350* on those 70* days and I've since then become brazen and lowered the stove to 290*. Never really took that into account.

I just get paranoid, ya know? This being my first year of burning coal and not really knowing what to expect on certain days.

I think I'll try running a 4" brush down the chimney just to knock the build-up out of the liner. The horizontal's are fine. Its the vertical run going to the chimney I saw there was ash building up on the inside of the corrugated liner walls.

I don't see a problem with cleaning the flue liner with the stove running. Don't forget to clean out the horizontal run afterwards though. Sometimes warm weather heating is a pain in the ash.

You're telling me Griz. Here I'm panicking because when it was 70 a few weeks ago the manometer never read below .03. This week it's been averaging high 40's low 50's and if I lower the air below the 3.5 setting on the t-stat it reads below .03. It scary cause I'm thinking there is something wrong with my chimney and there isn't.

My wife is off of work tomorrow so, tomorrow night I'll climb back up on the roof with the 4" brush duct taped to the fiberglass rods for the 6" brush and I'll clean what I can. Then vacuum the horizontal run.