Yet another "OWB on Anthracite" thread

OTR
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Post By: OTR » Sun. Dec. 30, 2018 3:27 am

Last year I bought a used Crown Royal 7200 wood boiler and put it in just before winter hit. Was a massive improvement to quality of life in the house - we'd been heating with a fisher wood stove and using the oil boiler for hot water when needed. It took a while before I was used to washing my hands in warm water again!

I've been interested in finding alternative fuel sources as I'm spending too much time processing firewood. The boiler is advertised as working with wood, coal, or corn cobs. Not even sure where I could find a reliable supply of corn cobs, so here I am at the coal forum.

I had all of the normal problems/noob issues associated with burning coal in an OWB - not putting enough in, stirring the coals like it was a wood fire, etc. Once I realized the need for a deep coal bed and more regular airflow, things were working pretty well - I got it into a rhythm of feeding it one 40lb bag every 12 hours and reducing the temperature differential to 5 degrees instead of 10 (setpoint of 170 at the time).

However, things were not perfect. Two primary issues:

1) The unburned coal that piled up on the sides would work its way down to the grates and get stuck, limiting the amount of rocking I could do (or outright eliminating any rocking ability).

2) Lots of clinkers. Probably exacerbated by me thinking they were unburned coal and throwing them back into the bed.

Did a lot of reading here and on some other coal burning forum and decided to try limiting the coal bed with firebrick, as has been suggested by numerous people. So I let the fire die down, emptied it out, bought out all firebrick in a 50 mile radius, and fabricated a metal frame. The grate opening is 1 firebrick wide - I think that's slightly over 9 inches - and there is a .3 firebrick ledge in the front and a 1.3 firebrick ledge in the rear. So I made the frame to enclose the grate area and nothing more. The frame rests on the door ledge, so the firebrick that stands on top of it is ~3-4 inches above the top of the grates, making the bed 12-13 inches deep.

Total bed dimensions are approximately 27" long by 13" deep by 9.5" wide.

Put it all together... and the weather switched from cold to 50 degrees. Decided to try it anyway, but the lack of need for heat made it very easy to fail. No big deal, cleaned it out and ran dinky pieces of firewood for a couple of days until the cold returned. That was interesting in its own right - the concentrated airflow burned the wood a lot more intensely than it usually does.

Got the thing all fired up now, and it looks like it's burning the coal much better. The entire bed is orange from front to back and side to side. The rockers are working with nothing getting stuck in them (so far). I moved the set point up to 180 and the differential down to 2 degrees. Not sure if I'm going to stick with that or not, will have to see how things perform.

Couple of pics, one with flash and one without. Left side of the bed is leaning in a little but I think that's from my wife loading wood behind the brick this morning (I guess my instructions weren't clear in that area, hah). Nice low blue flames when the blower is off and beautiful straight tall blue flames when it is on.

ImageImage


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coaledsweat
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Post By: coaledsweat » Sun. Dec. 30, 2018 6:06 am

Add more coal, go right to the top of the bricks. And service it before it burns through the top layer. You always want to see raw coal on the top.

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artbaldoni
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Post By: artbaldoni » Sun. Dec. 30, 2018 8:18 am

Thinking of bricking down my OWB too. Maybe limit front to back. Although I have a good system down and have been burning for 2 weeks this year without an outage, and thats with the warmer temps so lots of idling. Looks like
i'll be using about a ton a month.
Image

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BunkerdCaddis
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Hand Fed Coal Boiler: New Yorker WC-90 or more likely a Van Wert VW85H [to be installed (soon, very soon)(well not as soon as I had anticipated]
Hand Fed Coal Stove: Waterford 105 pulling duty, Saey Hanover II getting dressed for the party
Coal Size/Type: pea/nut
Other Heating: oil fired hydronic
Location: SW Lancaster County

Post By: BunkerdCaddis » Sun. Dec. 30, 2018 10:01 am

What size coal are you guys using?

OTR
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Other Heating: Crown Royal 7200 (OWB)

Post By: OTR » Sun. Dec. 30, 2018 10:26 am

coaledsweat wrote:
Sun. Dec. 30, 2018 6:06 am
Add more coal, go right to the top of the bricks.
Yeah, that picture was taken as I was about to put the next bag in. Once the next bag was in, the coal was a round heap over the bricks.
coaledsweat wrote:
Sun. Dec. 30, 2018 6:06 am
And service it before it burns through the top layer. You always want to see raw coal on the top.
Huh. I don't even know if that's possible here. I only see raw coal for the first hour or so of a 12-hour burn.

OTR
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Post By: OTR » Sun. Dec. 30, 2018 10:32 am

BunkerdCaddis wrote:
Sun. Dec. 30, 2018 10:01 am
What size coal are you guys using?
Still not sure. I was using stove coal before I built up the firebrick. Since I built the firebrick, I've been using nut.

My primary concern as it relates to size is stuff getting stuck in the rockers. I thought stove coal, being larger, would be the way to go, but now I'm rethinking that. I suspect the nut coal will burn into even smaller pieces by the time it gets to the grates, and it is certainly burning it without issue. So I think I'm going to stick with that.

lzaharis
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Post By: lzaharis » Sun. Dec. 30, 2018 10:47 am

artbaldoni wrote:
Sun. Dec. 30, 2018 8:18 am
Thinking of bricking down my OWB too. Maybe limit front to back. Although I have a good system down and have been burning for 2 weeks this year without an outage, and thats with the warmer temps so lots of idling. Looks like
i'll be using about a ton a month.
Image

=============================================================================================

Hello Art,

Don't hesitate about lining the boiler with firebrick the taller the better as the heat will be more concentrated and you will have fewer clinkers and a finer ash. Line it on both the front, sides and the back you should be able to find it at Lowest at about $2.79+tax per brick or if you know of a large brickyard within 50-65 miles they will cost much, much less per brick and you will be able to pay cash for them.


Leon

lzaharis
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Posts: 1603
Joined: Sun. Mar. 25, 2007 8:41 pm
Stoker Coal Boiler: Keystoker KAA-4-1 dual fuel boiler
Coal Size/Type: rice/buck mix
Other Heating: kerosene for dual fuel Keystoker/unused
Location: Ithaca, New York

Post By: lzaharis » Sun. Dec. 30, 2018 10:54 am

OTR wrote:
Sun. Dec. 30, 2018 3:27 am
Last year I bought a used Crown Royal 7200 wood boiler and put it in just before winter hit. Was a massive improvement to quality of life in the house - we'd been heating with a fisher wood stove and using the oil boiler for hot water when needed. It took a while before I was used to washing my hands in warm water again!

I've been interested in finding alternative fuel sources as I'm spending too much time processing firewood. The boiler is advertised as working with wood, coal, or corn cobs. Not even sure where I could find a reliable supply of corn cobs, so here I am at the coal forum.

I had all of the normal problems/noob issues associated with burning coal in an OWB - not putting enough in, stirring the coals like it was a wood fire, etc. Once I realized the need for a deep coal bed and more regular airflow, things were working pretty well - I got it into a rhythm of feeding it one 40lb bag every 12 hours and reducing the temperature differential to 5 degrees instead of 10 (setpoint of 170 at the time).

However, things were not perfect. Two primary issues:

1) The unburned coal that piled up on the sides would work its way down to the grates and get stuck, limiting the amount of rocking I could do (or outright eliminating any rocking ability).

2) Lots of clinkers. Probably exacerbated by me thinking they were unburned coal and throwing them back into the bed.

Did a lot of reading here and on some other coal burning forum and decided to try limiting the coal bed with firebrick, as has been suggested by numerous people. So I let the fire die down, emptied it out, bought out all firebrick in a 50 mile radius, and fabricated a metal frame. The grate opening is 1 firebrick wide - I think that's slightly over 9 inches - and there is a .3 firebrick ledge in the front and a 1.3 firebrick ledge in the rear. So I made the frame to enclose the grate area and nothing more. The frame rests on the door ledge, so the firebrick that stands on top of it is ~3-4 inches above the top of the grates, making the bed 12-13 inches deep.

Total bed dimensions are approximately 27" long by 13" deep by 9.5" wide.

Put it all together... and the weather switched from cold to 50 degrees. Decided to try it anyway, but the lack of need for heat made it very easy to fail. No big deal, cleaned it out and ran dinky pieces of firewood for a couple of days until the cold returned. That was interesting in its own right - the concentrated airflow burned the wood a lot more intensely than it usually does.

Got the thing all fired up now, and it looks like it's burning the coal much better. The entire bed is orange from front to back and side to side. The rockers are working with nothing getting stuck in them (so far). I moved the set point up to 180 and the differential down to 2 degrees. Not sure if I'm going to stick with that or not, will have to see how things perform.

Couple of pics, one with flash and one without. Left side of the bed is leaning in a little but I think that's from my wife loading wood behind the brick this morning (I guess my instructions weren't clear in that area, hah). Nice low blue flames when the blower is off and beautiful straight tall blue flames when it is on.

ImageImage

============================================================================================


Hello OTR,


What are your low and high limits??

You can operate at 140 low 160 high with a 10 degree high limit differential and make plenty of heat with a dump zone temperature of 190.


OTR
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Post By: OTR » Sun. Dec. 30, 2018 11:10 am

lzaharis wrote:
Sun. Dec. 30, 2018 10:54 am
Hello OTR,


What are your low and high limits??

You can operate at 140 low 160 high with a 10 degree high limit differential and make plenty of heat with a dump zone temperature of 190.
I have two settings on my boiler, the shutoff temp and the differential. Before the firebrick, I had the shutoff at 170 and the differential at 5 (so the blower would kick on at 165 and off at 170). Now, I'm running the shutoff at 180 and the differential at 2.

lzaharis
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Stoker Coal Boiler: Keystoker KAA-4-1 dual fuel boiler
Coal Size/Type: rice/buck mix
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Location: Ithaca, New York

Post By: lzaharis » Sun. Dec. 30, 2018 11:38 am

AH, now as I understand it, in this unit ]you are using a single digital aquastat for the high limit control on this boiler to maintain wide open burn as needed due to the open system boilers design. With it adjusted as it is you have a high limit of 180 degrees Fahrenheit with a differential low limit cut in of 2 degrees.

OTR
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Post By: OTR » Sun. Dec. 30, 2018 12:18 pm

Spot on, Izaharis. I think a lower limit and larger differential would work fine, but the fuel consumption doesn't seem to be much different with it set as is. I'm thinking the higher limit/lower differential may help avoid the clinkers I was seeing when burning without firebrick.

Unfortunately, my wife tossed wood on the coal bed this morning. From what I've been reading, the ash from that may form into clinkers later on. Oh well. Now she knows we're on coal and she no longer needs to feed the thing.

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BunkerdCaddis
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Posts: 379
Joined: Sun. Jan. 18, 2015 10:26 am
Hand Fed Coal Boiler: New Yorker WC-90 or more likely a Van Wert VW85H [to be installed (soon, very soon)(well not as soon as I had anticipated]
Hand Fed Coal Stove: Waterford 105 pulling duty, Saey Hanover II getting dressed for the party
Coal Size/Type: pea/nut
Other Heating: oil fired hydronic
Location: SW Lancaster County

Post By: BunkerdCaddis » Sun. Dec. 30, 2018 2:09 pm

OTR wrote:
Sun. Dec. 30, 2018 10:32 am
Still not sure. I was using stove coal before I built up the firebrick. Since I built the firebrick, I've been using nut.

My primary concern as it relates to size is stuff getting stuck in the rockers. I thought stove coal, being larger, would be the way to go, but now I'm rethinking that. I suspect the nut coal will burn into even smaller pieces by the time it gets to the grates, and it is certainly burning it without issue. So I think I'm going to stick with that.
I had a Mahoning OWB for years, burnt mostly wood in it but occasionally burnt some coal when winters were bad and I got low on wood. Used only stove size but I found overly aggressive use of the shaker caused more problems than not, I generally never had to use it for wood. If it's decent coal it should still burn into a decent ash. I would just "rattle" the grates enough to get air flowing and still let ash on top of the grates.

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artbaldoni
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Stove/Furnace Model: NCB-175
Location: Newville, PA

Post By: artbaldoni » Sun. Dec. 30, 2018 3:37 pm

lzaharis wrote:
Sun. Dec. 30, 2018 10:47 am
=============================================================================================

Hello Art,

Don't hesitate about lining the boiler with firebrick the taller the better as the heat will be more concentrated and you will have fewer clinkers and a finer ash. Line it on both the front, sides and the back you should be able to find it at Lowest at about $2.79+tax per brick or if you know of a large brickyard within 50-65 miles they will cost much, much less per brick and you will be able to pay cash for them.


Leon
Leon,
I don't want to get too crazy. I still want to be able to burn wood as well.

lzaharis
Member
Posts: 1603
Joined: Sun. Mar. 25, 2007 8:41 pm
Stoker Coal Boiler: Keystoker KAA-4-1 dual fuel boiler
Coal Size/Type: rice/buck mix
Other Heating: kerosene for dual fuel Keystoker/unused
Location: Ithaca, New York

Post By: lzaharis » Sun. Dec. 30, 2018 9:43 pm

No worries Art,
firebrick is a sponge when it come to wood or coal burning my friend.

OTR
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Post By: OTR » Tue. Jan. 01, 2019 5:40 pm

Aight, well, I was not happy with how that setup played out. The coal bed was not big enough to get a proper burn duration and it pretty much killed the ability to load any significant amount of wood. On top of that, the metal I used to frame things out was melting away, heh.

So I took another whack at it. Doubled the width of the bed, added firebrick to protect the metal frame, added angled sides. I can load lots of wood in it again, so that functionality is preserved. Will be getting the coal going tonight and come back with a report after sufficient test time.

The angled sides are double-layered, plus one row behind that laying the other way. I may remove one layer in the future. A pic of the current setup is below. It ain't pretty, but I think it - or a descendant of it - will be pretty close to the final solution. The pile of bricks in the back is to block up to the grates.

Image

Note my reuse of a lawn mower blade to hold the frames apart :lol:


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