Strange observation/question?

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63roundbadge
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Post by 63roundbadge » Mon. Apr. 16, 2018 2:33 pm

Hi, I've not been on here for over a year, my hopper-fed Alaska Kodiak been working perfectly so no concerns. I had a shoulder replacement so Mom has been tending/shaking/feeding the stove for 2.5 months. I'm back at it for 3 weeks, and there are 2 large fused pieces larger than the size of a grapefruit that won't break up. She mentioned this during her tenure but I couldn't deal with them. They glow red, and did not get any smaller. I've since cleaned out the stove over the hot weekend and I had to break one up with a chisel to get it past the hopper to remove it.

I've restarted the stove with this crappy weather, it's easy to start w/charcoal and it will idle at 120 degrees at the exit.

I thought the presence of major clinkers was a bad thing, but now I realize why I've used less coal this year all other things being the same. These tumors have taken the place of a bowling ball's worth of coal each day and glowed red and given off heat. To this I am thinking about finding ceramic replacements for them next year and allowing them to take the place of that much usable coal. Kind of like putting a brick in the water closet to displace the water to lessen usage?

Am I way off in my thinking here? 3 months of shaking didn't chew them up or wear away the bottom of them. They were not flat on the bottom from shaking.


Opinions please. Thanks!

 
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Post by freetown fred » Mon. Apr. 16, 2018 3:40 pm

I got nothing R, except Mother Earth's got a sense of humor. I'm sure you'll get a better answer from our resident chemists but that one works for me!! LOL Glad your up & runnin again. PS--just to sound somewhat technical--some sort of iron based build up-
Last edited by freetown fred on Mon. Apr. 16, 2018 5:37 pm, edited 1 time in total.

 
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Sunny Boy
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Post by Sunny Boy » Mon. Apr. 16, 2018 4:10 pm

Glad your on the mend, 63.

There are a number of things that contribute to clinker formation.

1. Some coal clinkers more easily than others. Some coal also has a lot of iron in it that can fuse together like over-sized pieces of welding slag and become impossible for grates to break up.

2. Then there's the design of the grate system. The older stoves that have rotating toothed grates tend to be better at breaking up the clinkers daily while they are still in the "crumbly stage". Let them stay in too long and they become bigger and harder. Some grate designs don't do much to break up the crumbly stage clinkers. They need more work during ash shaking time using a long right-angled poker, or slashing bar, to get in, either from under or above the grates, to break up the clinkers by hand tool.

3. An inexperienced operator who does not fully understand the need to clear ash correctly can "grow" some museum quality clinkers in as little as a week, or two. :o

4. Stirring the ash from above with a poker, to help move it down through the grates, can actually push the ash together when it's at it's fusing temperature - which starts at about when the firebed is glowing bright orange to yellow. You can feel the coal in the firebed get "soft" as you move the poker around. That's why coal stoves have shaker grates, so that you DON"T have to stir the firebed to remove ash, like you can with a wood stove.

As for fine tuning ash removal technique to reduce chances of clinker buildup, there's plenty of guys here can advise you with what works well with your type of stove, if you wish.

Paul

 
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Post by rberq » Mon. Apr. 16, 2018 4:37 pm

63roundbadge wrote:
Mon. Apr. 16, 2018 2:33 pm
These tumors have taken the place of a bowling ball's worth of coal each day and glowed red and given off heat. To this I am thinking about finding ceramic replacements for them next year and allowing them to take the place of that much usable coal. Kind of like putting a brick in the water closet to displace the water to lessen usage?

Am I way off in my thinking here?
My first reaction was, yes, you are nuts -- sorry, I mean you are way off in your thinking. ;) The clinkers glowed red only because the coal around them heated them up; they were not producing any heat of their own. But on second thought, you mentioned using less coal this winter. So MAYBE, just MAYBE, your "normal" firebox (without clinkers) contains so much burning coal that the body and surface of the stove can transfer all the heat to the house -- losing heat up the chimney??? Maybe a couple bricks in the firebox would better balance the heat produced with the radiating capacity of the stove.

I'm not sure my theory makes sense, either. Since Mom produced the good effects, perhaps the best answer is for her just to keep the stove-tending job. Don't tell her I said so. :lol:


 
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Post by franco b » Mon. Apr. 16, 2018 5:21 pm

As rberq stated the clinkers do not produce any heat on their own.

They might however increase the radiant energy in the same way old time gas fired space heaters used ceramic elements heated red hot by the gas to increase the radiant effect. The blue gas flame does not radiate heat well.

 
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Post by SawDustJack » Mon. Apr. 16, 2018 5:24 pm

I kind of agree with the others on the heat output of a clinker or the lack of heat output.... but on cutting down on coal used by taking up space... I don't think that is too far fetched. I have read on here that other people will cut down on their firebox size in the spring and fall by using firebricks to take up space. I have not done this as the stove I run the most already is a fairly small firebox compared to others. Well, then there is this lack of spring this year so I haven't even considered it! Still burning strong these days!

 
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Post by windyhill4.2 » Mon. Apr. 16, 2018 8:12 pm

Are you burning the same brand coal this season as you burnt the other yrs ? A change in brands can easily change the amount burnt.

 
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Post by 63roundbadge » Tue. Apr. 17, 2018 4:23 pm

Thanks for the responses, that's what I figured. I was only displacing raw coal and shrinking the firebox. I throttle my Kodiak when I don't need a lot of heat by letting the corners go dead, and only shaking the round grate or if I need more heat I'll poke the front 2 or all 4 corners. Right now with 45 degrees out I have the primary air totally closed, the MPD closed and it is still idling at 120. Just enough to keep the chill out.

I've thought about it for next year, I may pick these or something similar up:

https://www.amazon.com/dp/B01N9VMLGH/ref=sspa_dk_ ... rd_w=5Odc7

They're round, 2-3 inches so they wouldn't act as clinkers and jam the shaker. Since they're ceramic maybe they would take heat, glow and not wear away? They could take the place of the large clinker and be predictable as to decreasing the size of the firebox. Great in the beginning and end of season, and I could remove them at a December cleanout which I keep promising I will do but never do... They run so much better after that.


 
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Post by Lightning » Wed. Apr. 18, 2018 8:41 am

Like Paul mentioned all anthracite is not created equal, I had a batch that clinkered terribly my second or third year. My experience was that the fused ash just took up space in the fuel bed which decreased heat output and shortened time between tendings. About once per week I would use a hooked poker and "fish" them out of the coal bed after shaking ash and before loading a fresh batch. The fishing method worked really well and I was able to keep the fuel bed free of the fused masses without doing a total shut down and clean out.

Clinker Removal? Time to Go Fishing!

 
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Post by Sunny Boy » Wed. Apr. 18, 2018 9:12 am

If you don't clear them out on a regular basis the clinkers will start to fill in the bottom of the firebed. Yes they glow, but they don't produce heat, they absorb it. And since they are taking up space for burning coal, they will reduce the BTU output as they accumulate.

Simple test.
Compare how well your stove puts out heat the first couple of days after a shutdown, firebox cleanout, and restart, to how well it heats after running a month or two later as the clinkers take up space in the firebed.

Case in point.
I've been through this problem with a smaller firebox stove and it becomes very noticeable quickly.
The inner most grate in my kitchen range was warped so badly that both grates could not be turned to daily grind up the clinkers while they were still crumbly. I could only do the shaking which didn't get rid of the clinkers. After about a week the stove would not put out as much heat because the clinkers grew and took up space needed for coal that could burn. By the end of a month we could barely get the oven up to 250 degrees.

I'd have to shut the stove down and clean the layer of clinkers out the bottom of the firebox. Sometimes half the firebed was clinkers, so I was only able to get half the heat output even though I could see the underside of the firebed was glowing.

After each clean out, the fresh firebed produced far more BTU's and could easily drive the oven up to 450F. But the clinker cycle would start repeat after a week.

I finally gave up looking for replacement grates (very rare model stove) and used the one good grate to have new ones recast.

With the grates now working as they should, I can grind and dump the clinkers each morning before refilling with fresh coal. Because the firebox holds more burning coal the range produces plenty of heat and there's no need to shut it down, so it can run nonstop all winter the way it was designed to do.

There's a reason the antique coal stoves have grates designed to grind and dump the clinkers. The builders knew that clinker accumulation will reduce the heat output ability of a coal stove.

The problem is many modern coal stoves are originally designed for wood and therefore not good at getting rid of the clinkers without getting in there with a poker/scraper tool to break them up first.

Paul

 
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Post by CapeCoaler » Wed. Apr. 18, 2018 9:21 am

Ceramic fiber is not the same as a ceramic ball or brick...
Like the ceramic logs they will break very easily...

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