Unburned Coal...I Know...

Coal bed thickness is not adjustable in a koker. There is a short plate that covers the stoker end of the grate, almost as high as the side walls. As the coal is pushed forward, it is forced under this plate which results in coal depth being a consistent ~1.5 inches across the entire grate.

I am a little late to the party, but.....If that pic in the first post was full burn, the flames look kinda small to me and there is a wider ash band than I am used to seeing. Anybody else have an opinion on that?

At full burn, I would expect flames at least 12" high and about a 1" band of ash at the end of the grate. But I am used to seeing the flame & ash band on my mag, maybe a koker is different?

If at full burn the flames are not that high on mine I would look for something blocking the combustion air....combustion fan seated properly in mounting bracket, restrictor plate on combustion fan, clogged grate holes, fines built up under the grate, etc.

If the ash band is wider than 1" at full burn then I would look to increase the feed rate a slight bit.

I would only make one change at a time though so you can gauge the effect.

The pic of the burn might not have been full burn. Mine will have 12" flames and have only about 1" of ash on the end. His looks like mine does on an easy burn day…just loafing along.

She also suggested backing off the t-stat to reduce clunkers,

That makes no sense to me...you would back off the combustion air to reduce clinkers...anyhow, no worry for you.

I do believe the stove was just burning along easily. It was a warmer day in the low 20s after all. 1200 for coal is better than 2700 for fuel oil but if I can knock that down to 1000 by adjusting, that be even better.

Its the coal. The ash from my koker looked just like yours last year. This was my first year with it and assumed that is what it was supposed to look like. This year i'm burning same brand and size and I almost have no unburnt coal in my ash. I thought it was my imagination or stove was running different however when I ran a couple bags from last year I started to get a lot of unburnt again. Guess the coal varies year to year.