Outdoor Wood Furnace Info
All-Purpose OWF Discussions => Fire Wood => Topic started by: mtoll on February 09, 2014, 02:23:40 PM
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anyone burn coal as opposed to wood ?
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We don't grow it up hear in the northeast so not many of us including me would burn it.
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I've burned my fair share in the past but right now I'm trying out a wood only furnace.
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On week 3 of the great coal experiment. Seens to work ok if I mix in some wood. Can't get it to run on just coal. Cobbled together a better grate to allow for shaking and more even air flow but still no luck on coal only.
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I have been burning lignite coal out of North Dakota all winter and have burned alot of it. It is fairy poor in terms of btu's but it burns well. I just put a couple small pieces of wood in first then put 5- 5 gal buckets of lump coal on top. Gets me 12 to 14 hours. That doesnt seem like alot of time for the amount of coal but like I said it is lignite coal, way different than anthracite or bitumious. And it is also fairy cheap if you pick it up yourself.
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Artbaldoni does your NCB 175 have shaker grates. If not would it burn coal better with them. Has the mix of coal and wood extended your burn time given you a hotter fire? I'm not familiar with different grades of coal but could it be the grade of coal that it will not burn. I'm thinking that mixing both would be a good combination. I'm interested in trying this approach
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Sdrockhuler that interesting. I don't always have wood but live I live in coal country. I have not bought a boiler but I would like a boiler that you can burn wood and coal. I have been comparing boilers that will burn both.
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mine is a portage and main ml30 with shaker grates. Glad I went with the shaker grates.I am on the second year and this year has been a real test with as cold as its been here in SD. Was originally not going to get the shakers but its not much more money. I haul gravel and asphault and was close to coal so I bought a whole truckload and am glad I did. alot easier than cutting wood and a whole load (16 ton) costs under 500 bucks. Takes awile to get used to burning it as I didnt know anything about coal...
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@mtoll
When I can keep a fire it cuts wood consumption by 50% or better. Trouble is keeping it fired.
No shaker but the grate I fabbed can be shaken to remove ash. At 2100 yesterday with a mix of wood and coal I had a beautiful fire, blue flames dancing,etc. Went out this AM and cold as ice, ok not really that cold but no fire.
I think the issue is that the idle time allows the fire to actually go out. I tried propping the damper flap open (when the blower shuts off) with a stick yesterday but it gave me and overfire condition - 200+°. That was with a pencil sized (1/2") opening on the flap. Got some 3/16" and 1/8" keystock to use for shims to try to dial the "constant draft" to just keep the fire going but no overfire. I will figure this out!
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Good luck Im pretty sure ill not get my unit in and up and running yet this winter but if I do it will be with a mix of wood and coal or just coal. Im pretty sure you would need shaker grates to make it work with only coal.
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Types of coal got me curious so I looked it up, http://www.worldcoal.org/coal/what-is-coal/ (http://www.worldcoal.org/coal/what-is-coal/)
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Mix of wood and coal still burning overnignt! Could it be I have this figured out?
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Way to go you have to share with us your combination of wood and coal
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On week 3 of the great coal experiment. Seens to work ok if I mix in some wood. Can't get it to run on just coal. Cobbled together a better grate to allow for shaking and more even air flow but still no luck on coal only.
What do you have your temperature differential set at? The conventional wisdom on here, even with a mixture of wood, is a 5 degree swing or somewhere thereabouts. The tighter swing keeps your coal burning.
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Diff is set at lowest possible 5° on the original Honeywell aquastat.
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Where would a person buy coal in South East MO?
I know my dad talks about burning coal as a kid. But I haven't seen any coal for sale around here.
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Update.
Still dialing in. The problem is that the coal fire goes out at idle. No work today because of the snow so I have a chance to experiment. I have the damper flap closing on a peice of 10 ga. wire leaving a small gap to allow some constant air. Fan has been off for several hours now and the temperature is VERY slowly dropping and there is still a nice orange glow in the coal. Waiting for the fan to come on to see if it picks up. If this setting works I forsee getting incredibly long burn times running coal.
May have to start selling the wood I cut and buying coal!
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update art?
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Fire got too low before the fan came on. Went out or would have if I didnt tend it and add a couple pieces of dry wood. Readjusted the "constant air" a little more open. Blower is now off and temp has climbed to 200+°. Watching carefully to make sue it does not boil. It should start to drop soon. Maybe the fan will never come back on until morning.
I've made about 30 trips to the basement, out to the boiler, back to the basement and back up the steps. That's just about enough for today!
May need a cycle timer for the blower.
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How about tightening up the differential a bit?
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Fire got too low before the fan came on. Went out or would have if I didnt tend it and add a couple pieces of dry wood. Readjusted the "constant air" a little more open. Blower is now off and temp has climbed to 200+°. Watching carefully to make sue it does not boil. It should start to drop soon. Maybe the fan will never come back on until morning.
I've made about 30 trips to the basement, out to the boiler, back to the basement and back up the steps. That's just about enough for today!
May need a cycle timer for the blower.
What you're describing is what a lot of company's dealt with trying to get shelled corn to work as a fuel for OWB. We had a Wood Master dealer right in town that had one of the first prototypes for a corn boiler, what a pain. Corn has to be mighty cheap to use as a fuel when wood can be had.
I messed around building one as well. Just built the fire pot to play with. A vertical pot force fed from the bottom burned the best, but was harder to light and maintain a fire during idle times, was also very finicky about fines in the corn, moisture and any broken kernels.
A horizontal fire pot was easier to fab up. Used one gear motor to turn the stirrer very slow, like 3-4 rpm. Corn burns incredibly hot, kept burning up the stainless steel I used for an agitator. Went with a piece of 3/4 pipe instead, drilled a 1/4 hole in it then welded a piece of 1/4" stainless pipe over the hole then forced air thru the 3/4" pipe to cool the stainless. That worked better, one motor for the agitator and another motor to feed corn separately with a on/off delay. Still couldn't keep it lit during idle times, would burn fine all day, but might or might not like an hour of idle time. Finally bought an electric pencil torch off the net, pump a certain cfm of air thru that and end up with 1500 degrees at the tip, used a set of timers to fill with fresh corn, then so much time on the electric torch, then the agitator and fuel feed. Worked like a charm, then corn went up enough that we could actually make money on it instead of losing money as soon as the seed went in the ground, whole thing is still back in the scrap pile.
Your ideal of a cycle timer for the blower sounds promising, might want to add a second high limit so if it does get around 200F it doesn't cycle.
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Slim, diff at tight as it gets, 5°. Just a no frills Honeywell a-stat.
Was awake most of the night with back spasms and didn't hear the oil kick on at all. Fought the urge to go look at the boiler until about 0530. Found a 6" deep, nicely burning coal bed, fan on, 175° water temp. This means that the boiler ran through at least 1 cycle since the fan was off when checked last night around 2100.
Turned the fan off, ran the poker along the grate under the coal bed to clear the ash, added 5 coal shovelfuls of wet stove size coal and turned the fan back on. Now I wait to see if it takes off.
Stay tuned, same coal time, same coal channel!
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You might try the Jonson A-419 aqua-stat controller, I'm running mine with a 1 degree differential on my chip boiler right now and it's set at 202 degrees F
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Sounds like it is going to be doable but tricky (Ï'm thinking boil over is likely in warmer weather)
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If your burning soft coal like run-of-the-mine or the larger nut coal you should be able to get about 10 - 15 degree differential. The biggest problem with burn times will be the coal burns up through until the blower motor doesn't have enough force to burn any higher. When burning coal I kept the flap open about 1/8 to 1/4 inch so the coals stayed to refire. Never burned hard coal, but guys I know did said it can be more problematic to get reigniting.
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You might try the Jonson A-419 aqua-stat controller, I'm running mine with a 1 degree differential on my chip boiler right now and it's set at 202 degrees F
Thanks slim. Will be putting one on this weekend. I had looked at Ranco but it looked like it was only 3° diff. Glad to find the A-419.
Also got some bituminous nut size coal yesterday. Mixing it with anthracite stove size. Stayed fired all night.
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Let us know how the bituminous does
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This bit is the shiz! Have had fire since yesterday at 1600. No problems. I put 3 pieces of wood in the boiler yesterday to get the coal mix started, have not put any wood in since. 100% coal burning well at 45° ambient, which means lots of idle time. No trouble refiring. Have tended/loaded 2 times since original fire. This will take me through tomorrow morning or maybe afternoon.
I will still burn wood beause I have so much available to me but I am sure liking the coal right now. We'll see how long the infatuation lasts...
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Update:
Johnson A419 installed today. Had to run a neutral wire to the A419. No big deal.
Temp set at 175°, diff at 2°. Damper full closed, no constant air. We'll see how that works.
Fan cut off at 175° just like it was supposed to. Temp climbed to 179° and seems to be holding.
Will check later to see if its has dropped.
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You are on to it! $75 a ton in my neck of the woods for bit coal. Have burned about 2.5 tons this winter!
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Send me about 5 tons of that $75 bituminous!
New mix, bituminous nut and red ash anthracite nut. By far the best!
https://www.dropbox.com/s/vxfuu9bib4oci0j/20140226_070112.jpg (https://www.dropbox.com/s/vxfuu9bib4oci0j/20140226_070112.jpg)
https://www.dropbox.com/s/oa8oq7t8p90d6fb/20140226_070122.jpg (https://www.dropbox.com/s/oa8oq7t8p90d6fb/20140226_070122.jpg)
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Update
Have burned no wood for three weeks now. Have gotten the hang of the coal routine. Fan off, shake, empty ash pan daily, fan on, forget it. Still loading 2x a day. Will likely use 1 ton of coal per month in average temps. Johnson A419 controller set at 180°, 2° differential. Have installed a Maverick ET-732 barbeque remote temp sensor. Now I can watch temps from the house.
Next project is an ambient temperature sensor that will use the A419s offset feature. It will offset the set point to 160° when ambient temp is above 55°. I also need to clean up the install, it looks like a rat's nest inside the stove back. Maybe a nice box to mount everytnig in...hmmmm...
Enough for now, off to cut wood! :thumbup:
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Have not made the switch yet I got the grates ready to weld but have just been loading 2-3 shovelfuls per loading and cut wood usage back almost half. I will make it till summer without having to crawl through the snowbanks to get more. As soon as it is warmer still 10 below at night. I will finish welding and use what I have learned to make the switch. Thanks for all the info.