I've been burning the FV for only a few weeks. Until this weekend I was getting good clean burns with just fairly clean white ash left. The last two days I've been running into excessive coaling which is cutting back on my heat output and my ash bed has more chunks left in it. Have good draft and am using the same marginal wood supply I've had all along. Process is I load the stove (move coals towards the back and then 3 or 4 splits into the box), leave vent open, cat bypassed for at least 15 or 20 minutes. Then I engage the cat and bring the air down to 1. After I see a rise in the STT I move the air down to around .75 or so. I am getting a good secondary burn which peters out at some point -which I read to be normal. Smoke output is the same as it has been - heavy when in bypass but steam (or nothing) when in cat. Wood is mainly oak (not sure if red or white) with an occasional piece of cherry mixed in. Last night I made sure to use just oak in case the cherry was leading to this. I know my wood isn't seasoned as well as it should be but, by the time this heavy coaling is occuring, any moisture (I would think) has been long driven off. Today I've decided to let the stove burn down as low as I can get it and then clean out most of the remaining ash to see if that helps to reduce this. Thoughts? Anything else I can try ? Is this just something I need to accept?