Unburnt Coal in Ash

 
rharris
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Post by rharris » Sat. Feb. 05, 2022 2:29 pm

I am new to burning coal at home and currently have an Alaska Stoker II. I'm using the stove to heat a 40x60x12 pole building that has the entire shell sprayfoamed and the highest insulated doors. The stove does a fine job of heating the building, but I seem to have a lot of leftover unburnt coal in the ash. I'm using about 140+ pound a day. The stove is a rear vent with about 9' of inside single wall and then insulated double wall through the wall and about another 7' up the outside of the building. Draft seems to be sufficient. I did install a barometric damper, but have not checked it with a manometer. The stove was used lightly, but in great condition. Blower's are clean, gaskets are good, and grate holes are open. I have attached some pictures hoping that I can confirm that there is excessive coal leftover and for some suggestions. I did try cracking a window in the garage after wondering if the building is too tight. I have tried different coal, and one of them is the same coal my buddy is burning without issue. I hope I can get it burning correctly and more efficient - it does provide great heat. Thanks in advance for any help.

Attachments

stove.jpg
.JPG | 52.1KB | stove.jpg
ash 2.jpg
.JPG | 146.3KB | ash 2.jpg
ash.jpg
.JPG | 82KB | ash.jpg


 
rharris
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Hot Air Coal Stoker Stove: Harman Magnum
Coal Size/Type: Rice

Post by rharris » Sat. Feb. 05, 2022 2:38 pm

I have also adjusted the feed rate from 3 down to 1 and the ash was consistent. I now have the Alaska thermostat control and have a simple thermostat on. It produces the same ash at any feed rate or idle

 
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nepacoal
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Post by nepacoal » Sat. Feb. 05, 2022 2:39 pm

Are you pushing burning coal into the ash bucket? Can you take a picture of your fire while it's running full out?

 
rharris
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Post by rharris » Sat. Feb. 05, 2022 2:52 pm

It is not pushing burning coal into the ash bucket. this picture is not full out, but gives you an idea of the burn. Am I correct in thinking that there is unused BTU in the ash?

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Burn.jpg
.JPG | 31.7KB | Burn.jpg

 
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nepacoal
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Stoker Coal Boiler: Keystoker KAA-4 / "Kelly" and an EFM 520 at my in-laws
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Post by nepacoal » Sat. Feb. 05, 2022 3:09 pm

Double post...
Last edited by nepacoal on Sat. Feb. 05, 2022 3:11 pm, edited 1 time in total.

 
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nepacoal
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Coal Size/Type: Buck

Post by nepacoal » Sat. Feb. 05, 2022 3:10 pm

Usually chasing unburnt coal in ash is a fool's game... There is almost always going to be some. It's just the nature of burning coal in a stoker. Your ash does look like it has excessive unburnt coal or slate in it. Are your flames touching the top of the stove? What is your barometric damper set at?

 
rharris
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Hot Air Coal Stoker Stove: Harman Magnum
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Post by rharris » Sat. Feb. 05, 2022 3:26 pm

When it is running harder the flames almost reach the top. Damper set at 4 on the dial. It bounces around a little.

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E1B0AA2E-A6A4-4444-AC1A-98A9E2F93308.jpeg
.JPEG | 257KB | E1B0AA2E-A6A4-4444-AC1A-98A9E2F93308.jpeg


 
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nepacoal
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Stoker Coal Boiler: Keystoker KAA-4 / "Kelly" and an EFM 520 at my in-laws
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Coal Size/Type: Buck

Post by nepacoal » Sat. Feb. 05, 2022 3:33 pm

The fire shape in that second picture looks really bad... It should be lit all the way across. That is only burning down the center. Is the coal coming down each side going into the ash pan unburnt?

 
rharris
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Post by rharris » Sat. Feb. 05, 2022 3:39 pm

That was when i first turned up the thermostat to get it off idle. it does burn all the way across. When i had it set on steady run (no stat) it produced the same ash. It would run full across. I plan on trying a harman magnum stoker next week so I can compare the two stoves. If the Harman produces the same ash, then i guess i have a chimney issue. I don't think that is the problem, i have seen worse chimney installs. I know a masonry chimney is optimum, but i wasn't willing to do that for a trial stage. I'm not sold on the coal for heat at this rate. I went through 800-1000# in a week.

Attachments

flame.jpg
.JPG | 44.3KB | flame.jpg
Barometric.jpg
.JPG | 41.7KB | Barometric.jpg
chimney.jpg
.JPG | 61.9KB | chimney.jpg
Last edited by rharris on Sat. Feb. 05, 2022 3:51 pm, edited 2 times in total.

 
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oliver power
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Post by oliver power » Sat. Feb. 05, 2022 3:44 pm

As mentioned, It's the nature of a stoker, and it looks as if you have more than usual. Try leaving the coal on the grate longer, which means cutting back on feed, and upping idle fire to reduce lag time. You want no more coal on the grate than needed to heat the area you are heating. Your consumption is a little high as well, considering you have spray foam. Could be the coal itself too. When people talk about max burn, and ashes being, lets say 1-1/2" from the end of grate, that is a misconception. What they are telling you is Max Capacity of your stoker unit. What you want is Max amount of coal NEEDED on the grate to do the job, NOT Max Capacity of stoker. Once you get your head wrapped around the concept, it will all come together. Less Feed, and More Intense Idle Fire.
Last edited by oliver power on Sat. Feb. 05, 2022 4:02 pm, edited 1 time in total.

 
rharris
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Post by rharris » Sat. Feb. 05, 2022 3:50 pm

oliver power wrote:
Sat. Feb. 05, 2022 3:44 pm
As mentioned, It's the nature of a stoker, and it looks as if you have more than usual. Try leaving the coal on the grate longer, which means cutting back on feed. You want no more on the grate than needed to heat the area you are heating. Your consumption is a little high as well, considering you have spray foam. Could be the coal itself too.
when i had the setting at 1 (0-6), i had the same ash content as when i had it set at 3. Now that i have a thermostat, it ramps at its own rate that is not controllable when it is off idle. I could go back to the constant setting, but it produced the same result in the ash pan.

 
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oliver power
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Post by oliver power » Sat. Feb. 05, 2022 4:09 pm

rharris wrote:
Sat. Feb. 05, 2022 3:50 pm
when i had the setting at 1 (0-6), i had the same ash content as when i had it set at 3. Now that i have a thermostat, it ramps at its own rate that is not controllable when it is off idle. I could go back to the constant setting, but it produced the same result in the ash pan.
Then try a bigger (more intense) idle fire. This will ignite the coal being pushed on the grate quicker. Again, Misconception. The idle fire is not about minimum fire, just enough to not have an out fire when no call for heat. It's minimum fire NEEDED to ignite the coal quickly, which reduces lag time. You don't want to run on the idle fire. The idle fire is for igniting the coal being pushed on the grate when a call for heat. I added more to my previous reply. Also as mentioned, it appears you have drag on the sides of the stoker bed. Try sanding the stoker bed with emery cloth. And how about the opening at the bottom of hopper? Is it opened up?
Last edited by oliver power on Sat. Feb. 05, 2022 4:20 pm, edited 3 times in total.

 
rharris
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Posts: 12
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Hot Air Coal Stoker Stove: Harman Magnum
Coal Size/Type: Rice

Post by rharris » Sat. Feb. 05, 2022 4:17 pm

I’ll pick the idle up and see what happens. I’m not sure about the opening at the bottom of the hopper. I’ll look to see if I can find what you’re referencing.

 
rharris
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Post by rharris » Sat. Feb. 05, 2022 4:23 pm

Here is the ash content that makes it out the chimney pipe. My buddy said he does not have this type of ash in his chimney.

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flyash.jpg
.JPG | 63KB | flyash.jpg

 
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oliver power
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Post by oliver power » Sat. Feb. 05, 2022 4:27 pm

rharris wrote:
Sat. Feb. 05, 2022 4:17 pm
I’ll pick the idle up and see what happens. I’m not sure about the opening at the bottom of the hopper. I’ll look to see if I can find what you’re referencing.
It's the opening at the bottom of the hopper where the coal drops in front of the pusher block. I opened mine up all the way to fit stoker unit.


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