heavy chunks in with ash

We've had a stoker for several years and have a reliable source delivering our coal. My husband deals with the company and he said this year they didn't tell him what type it is. In the past we've had different sizes but, this year it ranges from 3/4 inch to pea size with a flat finish. Unlike in the past, the ash can is extremely heavy and there are baseball size chunks of burned coal, mostly gray and brown in color. They break up pretty easily and there does seem to be some small pieces of black unburned coal, but not a significant amount. The ash can has very little ash in it. What's going on? I almost feel like we should chop it up and reuse it or set the hopper to slower so that it burns more completely. Thanks.
Missy

Post pictures of your coal & ash.... What type of stoker? The more info you give the better advice members can give you.

Might be some of that bargain coal???

How much did you get?

If you know what coal was delivered in years past try to find that same coal and get enough to fill the hopper and see if that changes the problem. Is the ash a different color(red or white) compared to other years.

Might be some of that bargain coal???

was thinking the same

It's a Keystoker 90/105 Stoker Stove. Parts of the clumps (on right in photo) will easily break apart, but other partsare hardened together and requires force to break apart. About 80% is clumps with just a little powdery ash similar to what we had in years past mixed in with the clumps. Original coal on left. We started the season with last years coal (rice I believe) and that was fine. It's just the new delivery that looks this way.

Time to get some different coal.

Can you elaborate, Rob? We have a large family and aren't in a position to just get rid of this years heating $$. We've been buying coal from our neighbor who is in the stone/cement business and he delivered the same stuff to himself and his relatives. If we've "been had" I'd like to know exactly what's wrong with this type of coal so I can discuss it with him. I will go over and look through his pile with a shovel to see if it's the same exact stuff, too, as I suppose he could have used another truck for his delivery, but he's always been an honest guy.

Sorry, I hit the send button too fast. The coal looks pretty large for your stoker, it appears to be large buck / small pea size (but maybe the picture makes it look bigger than it is). Is there an air adjustment on your stoker? I would reduce the combustion air and see if it helps reduce the clinkers...but in doing so you might end up with more unburned coal in the ash.

Regardless of the adjustments you make, I think getting through this coal is going to be challange.

i have a harman mag and at one point had the same problem, it would clinker up and want to block the ash from falling in the pan.the ash was more of a red color. i had to slightly slow down the feed, reduce the combustion air and lower the draft. this did at the time correct the problem. my understanding this comes from different grades of coal,with that batch of coal i seemed to get a little better heat per amount used. maybe it was my imagination but it did seem that way. i was using rice sized coal

I agree that if this is the Newport coal easing up on the air may help some. It definitely produces a more coarse ash than other coals I've tried, and leaves somewhat more coal unburned, but if you didn't pay too much for it, and can get it to hold the fire and make heat, those might be the things to focus on while you work through your supply.

Mike

It's possible it maybe Newport coal, from looks of ash and oversize rice. Ask your delivery guy if he's knows supplier of the coal... Agree with everyone on reducing feed rate and less air..

Thanks so much, I'll give that a try.