Picture! Lots of Unburned Coal in Koker!

This topic has been beat to death and I've researched every avenue but this has gotten out of hand. 3yr old koker160 direct vent, duct through house return and heat lines. I've tried many different coal brands and settings on the stove. The latest being opening the induction fan solo the way (the metal flapper). Along with opening the draft on the d.v motor all the way to maintain -.03 on manometer. Feed set at 9 turns out. House heats up great even on these -20 deg days. Its just I'm always finding black in my ash pan. So today I ran a sample through a strainer, about three or four scoops with both hand together. Then I rinsed and smashed all the granola looking ash to expose the unburned coal. See the picture please and let me know what you think. Thank you.

are you getting a good even burn across the grates? is it a straight burn edge, or kinda wavey or not even. ? do do you have a pic of a good burn on the grates? are the flames up fairly high when it burning good?

maybe some of the holes are plugged in the grates? it's just pushing some of the coal along and not burning, sometimes it rides on the edge of the grates and never burns. How about cleaning the fins on the impeller of the combustion blower?

I always have some unburnt, but NOT that much.

These pictures were just taken. Full burn, front of stove above the door is 400 degrees, exhaust pipe is about 150 degrees.

Those 2 pics look very different...are they suppose to look the same?

Please explain.

Looks pretty even across. Looks like you can increase the feed a little more for more heat. if you have 1" or less of ash and not pushing hot coals off, your set for a full burn. As for the unburnt, doesn't look like any are riding on the rails, unless you feed is too high and it doesn't have time to ash on the grate. But if thats a full burn, it should ash before falling off.

The first picture I was kneeling and the second one I was standing. This has me baffled, I honestly think I have a full bag of unburned coal in every ash pan.

I'm not familiar which the Keystoker unit, is there a cleanout to remove fines that fall under the grate or is disassembly required?

Does the stoker run full out for long periods of time to heat up the house or is it cycling a lot between full burn and 'pilot' mode?

400* above the door sounds a little on the low side to me if it has been firing for 30 minutes or so straight but not so low if the stoker is cycling a lot.

If it is cycling a lot, unburned coal is going to happen some, not as much as you are seeing but the fix would be different than if you are burning full out for long runs and getting that amount of unburned coal.

I don't like that you have the gate open all the way to get .03. Is the DV unit really clean? Is the fan blade deteriorated? Is the combustion air blower fan blades clean? Is this top or bottom vent? How much pipe is on it? Is this a newer tight home? Is it in a furnace room or a wide open basement? Has anything changed in the home? Any weatherization work done this year?

Yes, as does *oilman*, I thought it not best that the OP has to crank up the DV to get to the desired draft setting...something is a'muck.

The unit does cycle somewhat frequently, nothing out of the ordinary considering the house has cheap windows and 2x4 walls. I turned the combustion motor and d.v motor back to stock as I saw no positive results after 3 days of trial. BTW keystoker said this shouldn't be a problem (the aforementioned adjustments). The only other thing would be the length of the exist pipe. It's 12' horizontal run from the stove to the basesment blocks, with a slight upward slope.

UPDATE! I did the same sample testing on my stepdads joker as mine and found near identical results...hmmmm. We both have the units adjusted per factory settings and burn the same amount of coal, him a little less as he has a newer log home. He also has less of a horizontal run on the exhaust. I'm guessing this is the nature of the beast with these jokers.

I suppose it could be the coal supply you are using, assuming his was in the same delivery. If you can try a few bags of another brand for comparison that would be interesting.

When was the fly ash last cleaned out of that 12' horizontal run?

If more than a ton of coal been burned since the last cleaning you may want to check it.

We use different coal. I use jettison he uses blaschak, but I have used various over the past couple years. Neither of use have cleaned out as its been too cold lately. We've burned approximately 1.5 tons.

Another finding. I recall someone saying the kokers and other stokers may have too thick of a bed of unburned coal as it approaches the grate. So what I did was pull some burned coal off the end of the grate to reveal cross-cut of the coal as it burns. What I found was the coal that is touching the grate, the bottom 1/8", was where I'm getting unburned coal in my ash pan. My first response to this is to slow the feed rate, as the plate that determines the coal bed thickness is not adjustable, would this be the correct action to do?