Yet another "OWB on Anthracite" thread
Posted: 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.
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.