My AA 260M Boiler Is Constipated!!

Yes that's right, my Axeman-Anderson 260M boiler is constipated. Just like people, if you feed it really good, high quality food that doesn't have enough 'roughage' or fiber, it gets constipated.
When I was researching getting a semi-load of coal shipped to me in Michigan, I looked into buying really good coal. I decided on a deep-mined, very low-ash content coal. This coal is around 6% ash, and what ash it has, is a fine powder, about like a fine beach sand. what I planned on and hoped for was to only have to empty the big ashpan every 3-5 days. And since when I leave for work, I typically am gone for 5 days at a stretch, this would make maintaining the boiler much easier for my farm caretaker. I built a big coal hopper that can hold 2-3 weeks of coal. So the ashpan volume was my limitation.

Once I got my AA boiler up and running, I kept having very little powdery ash and lots of unburnt coal in the ashpan. The boiler heated really well, and I really like it, but I can't keep sifting the unburnt coal from the tubs of ash. I have been burning the shifted unburnt coal in the other boiler, with an underfeed stoker.

Each time I took the ash drawer/grate out it had a hard layer of packed-powder ash on the grate, and a layer of unburnt and partially burnt coal on top of that.

I tried changing the ashing process to the timer-controled method that AHS uses, but this didn't help. I tried different anthrastat [ash temp sensor] settings and still no luck.

The only thing that made my boiler work really well for a few days was to remove the ashdrawer/grate and clean it out, and start over with a fresh fire.

With the help of forum member gaw, who gave me the phone number of the AA serviceman who had serviced my boiler in it's original location, I have learned the reason for my problem. The serviceman asked about the ash characteristics of my coal. He told me that my type of very high quality, low ash coal works really great in hand feed stoves/boiler, and stoker stoves/boilers but will not work at all well in the AA design... He described the exact symptoms that my AA boiler was having.

The serviceman recommended getting a supply of coal that has higher ash content, but most importantly has ash that retains a hard, lumpy, crusty ash, even looking like partially burn coal lumps. This type of ash will not stick to the ashdrawer/grate, but will allow the grate to move under it and 'pump' the ashes out from under the fire.

I have a few tons of deep-mined, crusty ash coal that I brought back from the spring 'mines tour', so I'm burning it exclusively right now, I hope that it will allow the ashdrawer/grate to work properly. This is the same coal that Yanche is successfully and happily burning in his AHS s130 boiler, but my coal is Buckwheat size, Yanche's is Pea size. I should be burning Pea size too.

Nowhere did I find any reference to buying coal with hard crusty ash in the literature for Axeman Anderson, AHS or Eshland. This knowledge is apparently 'tribal knowledge' amongst servicemen working on coal boilers. The only comment in the manuals or in the 'Bureau of Mines Report' is that a coal with a high ash fusion temperature should be used. This reduces clinker formation.

I'll update in a few days to a week with how the AA boiler likes the coal from a different mine/breaker.

Greg L

Greg L

So its time for an enema?

Well, live and learn. That is very interesting, I'm glad you found the cause. It just sounds strange that the coal is "to good", but I guess those guys know their stuff.

Are they members of this board yet?

Feed the old girl some good old strip mined coal, the bone and shale will have her cleaned out in no time.

I have no such problems with my AHS S130. My ash however looks significantly different. It has both powder and granola cereal like look to it. The majority is crunchy pieces that break easily when rubbed between your fingers. My coal this season is deep mined pea coal from the Superior Coal Preparation Co. Their breaker processes coal from their own underground mines. Photos of how this coal ash looks is shown in the photos below. I've burned coal from other sources in previous seasons that has similar looking ash. The color and/or size of the "granola" lumps may have been slightly different but it was essentially the same. The total volume of ash from my current coal is less than half that from the Reading brand I was burning last season.

I like my AHS boiler a lot. If however, my first experience in using it would have produced the problems "GregL" is having I would have thought it's a piece of junk. No where in the documentation does it specify anything about the coal requirements other than it needs to be Anthracite pea sized. I've just lucked out and got the proper ash type coal from three different sources.

When you look at the flow path for the combustion air in the A-A, Eshland, AHS boiler it's obvious a powdery hard packed ash will restrict air flow resulting in atypical burning. The inlet combustion air must flow into the ashpan area around the solid grate and up through the coal bed. Fine powder ash makes this difficult and even worst makes the air flow uneven resulting is areas where coal is unburnt.

I wonder if I might have a potential problem. When I measure my "over the fire" draft I get wide variations, 0.10 to greater than 0.25 inches water. I suspect the variations are caused by the amount of ash inlet restriction. Large restriction resulting in a large "over the fire" measurement, i.e. the inspection plate is being sucked in harder. Do others with this boiler design see similar effects?

Greg,

I'm glad you have found a reason for the problems you've been having with the AA. I have some nice high ash strip mined coal I'd trade in a minute for the powdery stuff. I had a few nice sized clinkers that filled the palm of my hand this morning.

I guess that each different type of stove requires a certain type of coal to burn properly.

Hi gregg and yanche

I will let you know what happens when my ahs 130 starts burning the low ash (6-8) uae in a day or two. I just put 200 pounds on top of the strip mine coal that was in her. should be about 2 days. I hope all goes well. if nothing else I can mix it with the other 32 ton of strip mine I have on hand. should be a good experiment. I hope I have no problems. but thanks for the heads up gregg. Have a safe trip.

cougar

Greg, try some bagged Reading coal. That's the strip mined crap I use and while it burns hot the ashes are like little red metal kidney beans mixed with granola. I'll trade ya, I got 5 ton of the stuff in bags here in western NY.

Reading is actually pretty good coal. A lot of breakers mix in a little slate on purpose just to get good burning qualitys. Too clean of a coal might burn up to quickly or restrict your airflow. You have to have a nice mix to work good.

I bought 5 tons of Reading coal last fall ['06] when I was still hand feeding 'Big Bertha' my custom made boiler. The reading coal had lots of wood pieces, some rock and lots of ash. Other than the wood and rock, it would probably burn pretty good in my AA boiler. I may try to find some Pea size Reading Bagged coal from one of the farm/feed stores here in Michigan.

But I wouldn't recommend the coal for most other applications. I still have ~20 bags of Reading Nut coal, and hand fed some of it to my AA, it is pretty poorly cleaned and sorted. I had handfuls of fines in each bag, and at least one or two pieces of wood the size of my index finger in each bag...

My AA seems to like the different coal I'm burning. I may be making another 'pilgramage' to Pa for coal after Christmas.

Greg L

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Amazing, a coal burner that doesn't like the good stuff! I had a clinker jammed in the grates this morning. I managed to push the lever slowly almost all the way back on it dislodged without dumping the whole fire.

You would think that the coal you have there is the exception rather than the rule Greg. If they would have had that type of coal during the development of the Axeman-Anderson you would think that you would have at least heard of it and the potential problems or maybe the design would be a bit different than what it is today.
From the limited people I have talked to about A-A boilers, that have or had them, some unburnt coal will get by at times, mostly in the summer while just idling.
Hopefully a different type coal solves your issues and you can begin to enjoy a return on your investments in time and money.

On Monday the 17th when I get back to Michgan, I'm driving south to a coal retailer in northern Ohio. I'm going to buy a half ton of the strip mine pea-size coal he sells. With what I see in the photos of Yanche's ashes, the strip-mine coal should provide the 'roughage' needed to keep the ash sliding on the ashdrawer/grate in my AA boiler. Yanche's coal IS deep mined coal but from a mine where the coal has a much crusty-er and chunky ash.

I'm currently burning the buckwheat sized Superior deep mined coal [Yanche's mine, but different size] mixed with the low ash UAE coal. I'm burning the mix at the ratio of 2 buckets of Superior buck to one bucket of UAE pea coal. So far the only issue is that the buckwheat is pretty small and it doesn't let a lot of air up through the bed of ashes or the coal. so My max flue temps are down a little. But the grate does not seem to be getting clogged with powder ash, and the ashpan has mostly ash in it. not unburnt coal.

So if the strip mine coal [higher ash content, hard crusty ash] is the answer, it looks like I may have to make a road trip to Pa for 5 tons of superior pea coal not that Superior coal is strip mined, but it has hard crunchy ash, which I need instead of the fine powder in the UAE coal.

Greg L.

hi gregl

looks like the experiment on ahs 130 has began . looks like the uae made to the bottom now. getting alot more fine ash and less crunchy ash.... we will see.

cougar

Use the pea coal. I have burned better coal in my 130 than the Coal Contractors stuff I currently have in my bin and I have found that it didn't matter much. The better stuff was less work.

I have a 1980 boiler with a functioning grate switch I have it set to the about 140 degrees, with the shaker lever set at about two teeth. I don't use the hot water coil yet, but I run the t-aquastat at 140 as well.

Some other ideas:

You grate switch might be off. Some one could have turned it by hand not by Allen key.

Check the shaker to make sure it's shaking properly.

Your fire could just be too high, check the adjustments.

hi gregg

well the experiment has a interesting turn I will say. have been on uae coal for about 5 days now.I have found no coal pieces in my ash pan. I have alot less ash and lighter than my stripe mine coal. only other thing is my clinkers are bigger and harder???????? try to figure that out running stat at 180 degree water. I will keep using uae. only real bumber is I have less ash to put on the drive way grates running at 120 to 140 ....... ash temp...... hope things are staying warm for you

cougar