Do Stokers Have Clinker Problems?

I've been reading about clinkers & what a pain they can be. It seems this is happening on hand fired units. My question is.... does the automatic nature of a stoker drop the clinkers in the ash can? Or do they accumualte and need to be hand cleaned?

What a great forum!

Hi Freddy, yes some stokers create clinkers,, most are not a problem at all.. On WNY's keystoker, the end of the stoker's bed is near the front of the stove, so when the rice-size coal would slightly fuse into a soft pillow-like clinker, it would not drop off the end of the bed into the ashpan.. and coal and ash would back up behind the clinker.. this is the only instance that I have read about where a clinker caused a problem.. Like you suggest , most just fall off into the ash pan.

Clinkers form usually only when the fire is burning very hot.. most anthracite coal's ash-fusion temperature is over 2500*, so you have to be burning pretty hot to start to form clinkers.. But some of this depends on the coal as well,, if the coal is very low ash, clinkers form easier. Higher ash content tends to insulate the pieces from each other so they don't fuse together.. at least this is my 'theory' why low ash coal fuses into clinker easier.

The AHS and AxemanAnderson boilers make clinkers too, but the are ejected with the ash into the ashpan, so they are not a problem.. The EFM underfeed type stoker will have some clinkers, but they just fall into the ashpan,, if they hang up in the firebox, they are easy to see and push off the edge of the firepot and into the ashpan,, so again, not a big problem.

Hope this helps answer your question.
Greg L

If you get really bad clinkers its the coal.

Thanks for the answers. I feel better knowing they shouldn't be a problem.

It depends on the coal. Not a "normal" occurance with Stokers, but on occasion or if it's really, really cold and the stove is really cranking they will form. I get them in both the LL and Keystoker. Usually just the Coal Cakes, smaller versions of the clinkers that the hand fired guys get. But still a small fused together chunks. Sometimes they can jam and you will get some coal overflowing the sides of the burn grate, you can see the unburnt in the corners of the pan....

Here are some when it was really cold and the stove was cranking pretty good.

That doesn't happen with white ash.

WNY-where is that coal from in the photo?
I haven't had any problems like that with Superior buck in the Alaska.

Where your coal comes from will make a difference. I burned coal this season from 2 different suppliers and found I had more clinkers from one than the other. I have a Keystoker and like others have stated, I have not had a problem with them blocking the grate. They all just fell off into the ash pan. Also as they said, when I finally shut down for the season (last Sun) the stove was pretty much idling and I had no clinkers that I saw the whole week prior to shutdown. When I did get them they were all just small cakes as WNY said.

Some coal clinkers more than others. On some stokers if you can cut back on the air you can eliminate or cut down on the clinkers. I spoke to someone earlier in the year who had massive clinkers in an Axeman Anderson and he had to increase his ashing to resolve the problem because the A-A has no air adjustment. In most cases there is a way to work with a load of coal that is more prone to clinker.

Ahhhh, another tib bit of information to add to the decision of which boiler to buy. If the clinkers tend to form during high heat, high use periods, perhaps a larger boiler would be a better choice than a slightly smaller one. I'm sure a 90,000 BTU would heat my house, but it would be flat out to do it during the cold part of the year. If I got something in the 130,000 BTU range it wouldn't run as hot. You guys (and gals?) are the best!

Fred

Freddy wrote:Ahhhh, another tib bit of information to add to the decision of which boiler to buy. If the clinkers tend to form during high heat, high use periods, perhaps a larger boiler would be a better choice than a slightly smaller one. I'm sure a 90,000 BTU would heat my house, but it would be flat out to do it during the cold part of the year. If I got something in the 130,000 BTU range it wouldn't run as hot. You guys (and gals?) are the best!

Fred

I wouldn't recommend oversizing a boiler, especially to solve a clinkering problem. Size a boiler for the required load. Coal boilers have a wide range of BTU outputs because the fuel (coal) input can easily be adjusted. Any boiler runs most efficiently near it's peak output. I don't know if you want or need a back up boiler but one sizing choice would be to select a boiler size that would provide adequate BTU's on all but the coldest days. On those days the backup boiler would make up the difference. Such a design approach gives you a coal boiler that operates most efficiently, most of the time and provides heat in all but the coldest of days. Remember the coldest day of the season is a rare event. Smaller boilers are obviously less expensive and a small backup boiler can also be lower cost. A small propane boiler, or perhaps a commercial quality hot water heater would be possible choices. Sure propane is an expensive fuel but the overall capital costs might be lower and still meet the requirement of backup and coldest day heat.

Richard S. wrote:If you get really bad clinkers its the coal.

Richard S. wrote:That doesn't happen with white ash.

Thanks for the good replies. Love this place! Ohhhh, I finally found the donation button. I know the Forum requires some money to operate, so a small donation is on the way.

I'm so bad at decisions! As mush as I think the AHS S-130 is a sweetie, I vasolate between it and the Keystoker. The K-6 is only about $600 more than the K-2. If I build an addition to the garage and pipe the heat in I think the K-6 would be the better choice. It will end up heating the garage and they'll be some loss to the pipes. The K-6 would be about $1,400 less than the S-130 by the time it lands in my door yard. I do like the idea of the S-130 upgrade of the thermo ash monitoring system and the self cleaning that it's supposed to do. I don't like the high coal bin if I hand feed it.

I'll figure it out....soon!