Burning Coal In Modified Wood Stove

Peter, Sift threw the ashes and get out all the lumps and put them in a bucket near your stove. Whether they be unburned,partially burned or mostly burned doesn't matter. Get yourself a wood fire going and feed in a few scoops at a time till you have real good burn going. If necessary add a few pieces of wood to keep things going. I know it's a cardinal sin for coal to be stirred but in this instance it don't hurt, stir some of the coal over the burning wood embers evry once in a while. This will burn up the coal from the failed attempt and won't go to waste. It will also cut down on the amount of wood you are using. And it will also even out your heat temperatures.

I've used this method after my wife tried reviving a coal fire unsuccessfully. She was even quite happy with the results.There weren't the highs and lows like from a wood fire.

If the ashes and unburnt coal are still in the stove just try to get as much powdery ash down through the grates the best you can.This will help with the underfire air flow. Move the rest to the sides.Then build a wood fire in the center. Once you have a good fire going move the coal from the sides on to the fire. When it is all burning just add a bed of fresh coal on top.

Dallas & Linc:

Thanks to you both for the continued encouragement.

I cleaned the stove and grate again this morning, have a nice wood fire burning and will do (pretty much) as Linc suggested... but start with some fresh coal.

I also removed the top half of what is an improvised two part grate... hard to explain, but in normal operation, the bottom part rotates and knocks up against the top part... works fine with wood ash but it was the top grate that was giving trouble with the unburnt coal (I think), and it may be easier to keep the ash (and a decent draft) flowing without. We'll see.

Yeah, being used to a wood fire, it's easy to get impatient with coal, in terms of 'response times' when opening drafts or shaking down ash.

I know I shouldn't give up so quickly... and knowing me, likely won't... but yesterday was so bl**dy aggravating. Without any question, the experimentation is fun... it's only when faced with a certain repeat of failure that I lose enthusiasm.

I may just get myself in trouble again, but what I'm hoping (for the time being) is to keep a wood fire going in the back of the stove, and slowly add coal to the front (where the underfire air is directed)... and see if I can't keep both going with (mostly) underfire draft.

Sub-zeros predicted for tonight and tomorrow... need to get back down to the basement and tape a trouble lamp to the water main.

"More news as it develops."

Peter B.

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Peter B. wrote:I know I shouldn't give up so quickly... and knowing me, likely won't... but yesterday was so bl**dy aggravating. Without any question, the experimentation is fun... it's only when faced with a certain repeat of failure that I lose enthusiasm.----

Don't look at it as "failure", but "continuing education"! It will most likely work, but may not work as good as you had hoped for. At that point, you'll probably know it's limitations and the reason for them.

It's a beautiful stove, from the picture. Not nearly so utilitarian-looking as the rectangular steel machines most of us use. So I hope you can make it work. It's good you found anthracite -- though that's all I have used, it sounds a lot cleaner and pleasanter than what I have read of bituminous.

I did notice in one of your posts that you have air both below and above the fire, and that you shut off the under-fire air at night and the fire died. When first loading new coal it gives off some gases to be burned above the coal bed, so you want a LITTLE air above the coal, in addition to a LARGE amount from underneath. Other than the early part of the burn you want ALL or virtually all the air to come from below the coal, not like a wood fire. And you said you were still experimenting with a shallow coal bed. I know it's scary to really load it up with coal, but a shallow coal bed will NOT burn well if it burns at all. It's like an atom bomb, you need the critical mass to make it go. (Though I'm not sure that analogy will reassure you, either.)

Bear in mind also, in your next round of modifications, that when you burn coal you will have many times as much ash to dispose of compared to wood. So if the stove doesn't already have a goodly ash pan below the grates, try to allow for one. As you discovered, coal ash doesn't sift down through the grates nearly as easily as wood ash. So if you can get a look at the operation and the dimensions of the openings in some coal grates, that might help. The grates and the shaker mechanism should be pretty rugged -- my Harman manual mentions "grinding" the larger pieces with the grates so they will pass through.

Sorry to be beating this thread to death, and this is premature at best, but the different grate arrangement already looks like it might help. I'm able to shake down a few embers now readily... when yesterday I _flailed_ at the double grate and never managed more than a single at a time. I can hear the lower draft pulling now (couldn't yesterday) and the first light load of coal did more than sit there and look dark above the glow.

I'll likely run the 'dual fuel' mode until I've fired off the unburnt coal left behind by the previous two trials and gain more confidence that I *might* be able to run coal alone. For now, I need to be able to rake and poke the coal (occasionally) from above, in order to make sure it doesn't go out.

Given my previous missteps and what not, I'm still reluctant to go to a deep coal bed. I'm afraid I'd just have to dig out the stove again afterward... but I've definitely heard the recommendation.

If I get some more of the basics down, I'll probably be asking about 'particulars' soon enough.

I don't mean to seem smarmy every time I offer thanks, but I'm genuinely greatful (no pun) for the advice offered freely here. At this point in time, there doesn't seem to be a whole lot of other practical information or feedback available on the web.

For what it's worth, as my 'backup heat', I've got two oil filled electric radiators... and I used to say to myself "I'm burning coal, now." every time I turned them on.

Likewise off topic, but I spent a h*ll of a lot of time in trial and error trying to make the old stove more efficient and more trustworthy as a wood heater. It has served me real well in modified form for all of fifteen years. It would be a real treat (and a feather in the cap) if I learn how to shift back and forth between two fuels.

Have it good.

Peter B.

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PS - rberq - My Dad helped negotiate the Nuclear Non-Proliferation Treaty so the analogy to 'critical mass' wasn't lost.

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Peter, My sis-in-law and hubby live North of you. They are up in Rusk Co. It sure does get cold up there in Wisconsin. I thought it was cold enough at Thankgiving a few years back when I went up for the deer hunting. I don't need to imagine what it's like during the winter.

Nice stove. I don't imagine it has a very big firebox but try banking up the sides and back with coal. Right up to the top of the fire bricks. Just make sure you leave the lower draft open and an exposed area of glowing coals. If you haven't done it yet,make up a poker to go up through the grates from the underside to help loosen the ashes that may get packed.A wire coat hanger may work if nothing else is handy.

Mound the coal right up in the middle, just keep the sides at the top of the firebrick. The more you have in there burning, the harder it can pull through the ash layer. I burn less coal with more heat this way and have much better control. My boiler is basically a woodburner with a coal grate. The deeper I run it the easier it is to run, especially when it is warm out. A small fire is easy to run hot, not so when you don't need a lot of heat, it will bite you. When I run it even with the firebrick, I will need to shut it down, clean and restart it every three weeks or so. If I run it up into the water jacket and mound it up she will burn all winter until I shut it down. That's about 4" deeper, huge difference in performance. When I first bought the thing, the manual said fill to the top of the firebrick and thats what I did. When I had a conversation with a guy that was at the factory when they were made I asked him about it and he said to fill it right to the door opening. Worked a lot better that way, mounding it up was even better. I have a boiler, so burning coal against the steel is OK. I don't recommennd that with a stove however, but do mound it up as it should help.

Mixed results with the last trial...

A nice combination fire for a while... with wood for a quick heat boost and coal to sustain, but again ran into grate jamming and clogging.

I'm trying one more grate arrangement with materials on hand before I throw in the towel for now... but I'm pretty sure it's destined to crap out.

If I'd been able to burn even a small amount of coal (pretty much) completely, I'd jump on the idea of loading deeper... and the notion that that's in fact what's *required* for a good burn hasn't been (entirely) lost on me.

But the grate problem has me beat for the moment. Between the jams and the clogs, I just don't seem to be able to give the fire as much air as it wants... throughout the burn. Until I've solved that, I think I'll just run into the same problems repeatedly... regardless of bed depth.

I haven't exactly made any sort of study of grates for hand fired stoves either... I wonder if there's a thread here that shows a variety of different grate designs?

I think I'm going to have to back out of the coal biz for now... the stove needs an overhaul before next season anyway. Maybe I can incorporate a bulletproof grate for next year.

Thanks once more for the help and encouragement found here.

Peter B.

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Hello Peter, You should be able to burn a firepot full of coal without shaking or cleaning out the ashes.. Are you trying to shake down the ashes every couple of hours?? If so, is this because the fire appears to be starving for air?

Since your grate seems to be what you are focusing on, get a piece of steel rod, that is small enough to fit easily in the slots in your grate. a 1/4" or 3/16" steel rod or wire is what I used. The wire frame from a 'political sign' is a good source for the steel wire. Bend an 'L' on one end of a piece about 2' long, and a loop or handle on the other end. Use this poker to go in under the grate, through the ashpan door and poke up through the gaps in the grate, do this to dislodge the built up ash. If your shaking action and grate design isn't aggressive enough this poking with a steel finger should do the trick.

Now: this may be the real problem: you have a lot of sections in that ornate stove, and each section is sealed to the next, making a stack of iron cylinders, all sealed together at the joints.. a coal stove MUST have no air leaks letting the precious chimney draft leak into the stove except up through the coal bed.. I'm betting that you have a small leak here and there, around this door, this window, this plate, and the sum total of all the leaks is letting in too much air above the fire.
So what happens is that when the really hot fire starts to decline, there isn't enough draft pulling air through the bed of coals to maintain a hot fire, and the chimney cools some, further reducing the draft, and eventually the fire goes out. When you have a fresh fire with a clean grate, the airflow is less restricted, so you get enough air through the fire for awhile.

Can you use a candle, or a cigarette as a smoke source and run it by all the doors and section joints in the stove and see if you can locate and seal up some leaks?? If you have a manual damper in the flue, after the fire starts to die down you will need to open it up to keep a strong draft through the stove.

Hope this helps.. Greg L

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LsFarm wrote:Now: this may be the real problem: you have a lot of sections in that ornate stove, and each section is sealed to the next, making a stack of iron cylinders, all sealed together at the joints.. a coal stove MUST have no air leaks letting the precious chimney draft leak into the stove except up through the coal bed.. I'm betting that you have a small leak here and there, around this door, this window, this plate, and the sum total of all the leaks is letting in too much air above the fire.
So what happens is that when the really hot fire starts to decline, there isn't enough draft pulling air through the bed of coals to maintain a hot fire, and the chimney cools some, further reducing the draft, and eventually the fire goes out. When you have a fresh fire with a clean grate, the airflow is less restricted, so you get enough air through the fire for awhile.

Greg:

I think you may be right about this. Last night, I fed and 'watched' the fire closely, and shook down ash when the grates allowed. Most times, with a strong fire, I could hear the underfire draft pulling through the ashbox door.

I did NOT close the ashbox draft competely last night, and the fire was still going fine when I went to bed.

So either the grate clogged in the night or the overall draft pulling through the coal bed is just not adequate when the fire begins to taper off and the chimney cools.

It has always (of course) been just fine for a wood fire, and I've learned you could (judiciously) introduce secondary air anywhere on a stove you thought it useful. I've plugged one secondary draft, and I close the main secondary control on the fuel loading door when I'm done with wood and hoping to burn off the coal.

There are, I know, some (minor) additional leaks above the stove's main fire chamber and in at least one joint in the chimney. And yes, you're right the stove as a whole may be more than a little porous at the various joints.

I'm trying still another tack tonight, but likely won't load the coal bed deep.

I guess the only remaining question in my mind with respect to my half a**ed approach is whether - given sufficent temp and draft - I should be able to expect even a small, shallow load of coal to burn completely?

That would surely help to know.

Peter B.

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There is one other thing, which you might ponder. is there too much draft through the coal or over the coal at some times ... sucking the heat right out of the fire?

The answer to your last question is NO. Coal is not an independant burning fuel. It 's a 'community burning' fuel.. You can burn a single piece of wood. You cannot burn a single piece of anthracite coal. The coal needs the heat from the adjacent pieces of coal, they radiate heat back and forth, and the passageway between each piece forms a concentrated supply of combustion air pulling the heat and combustion gasses through the coal bed..

You really are doing yourself a disservice to not try a full load of coal.. Get the fire going strong, a bright red bed of coal and add coal as deep as you can, I think you said your firepot was about 11-12" in diameter and a firebrick [9"] deep. Load it full.
The full firebed has a different burning dynamic than a shallow bed of coal.. The ash will burn much more completely. Don't shake as much, use the wire poker from underneath to make sure the slots in the grate are open. DON'T worry about the coal... it will convert coal to heat and ash, the ash will settle down and fall through the grate.. Remember what coaledsweat said about his firebox?? if filled deep he can go all season without cleaning off the grate, if he uses a shallow bed of coal he has to clean off the grate every few weeks... The ash doesn't burn as well or as completely in a shallow bed.

The only thing you will have to deal with if it won't burn the deep bed of coals is a few extra handfulls of coal in the firepot, not a big deal... You need to try to burn the anthracite the way anthracite likes to burn:: in a deep coal bed.

If I were to design a new hand fired stove or boiler, it would have vertical walls on the firebox and the entire bottom of the firebox would be shaker grates, and the firebox would be at least as deep as it is wide or long... at least a cube.. The deeper the better... it works... it's the way anthracite likes to burn.

Greg L

Sorry about the nagging, but former wood burning folks [I was one too!! ] have a hard time getting the message...

GL

Should you expect a shallow bed of coal to burn completely? No. After an overnight burn, I can shake the ashes down to the point where I have a shallow layer of coal burning brightly on the grates, ready to dump fresh coal onto (immediately!). If instead of loading new coal, I leave it and come back in fifteen minutes, I will have a layer of cool gray-black chunks, far beyond saving the fire. The few times I have left a fire to burn out completely, so I could do maintenance or cleaning, there has always been about four inches of half-burned coal left when the stove cooled.

Okay...

It was impulsive and I hope to gawd I had enough coals to light it off, but I'm about 6 inches deep now.

Today (at 10 below) I learned that my (dam) electrics and a little propane heater can keep me from freezing, so Greg is right... there's not a lot more to lose than just cleaning out the stove again... I hope.

But Greg, you've forgotten... it actually takes three or four sticks to make a wood fire... unless you've got nothing but hot coals going on. Wood likes company too.

If tonight goes well, I'll come back and provide yet another report. If not, I might be back next year looking for more advice.

Anyone here sideline in homeowner's insurance?

Peter B.

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I'm afraid I didn't have much better luck with the deeper coal bed last night.

I had what seemed like a solid fire going, left both the underfire draft and the manual damper right where they were and went on to bed... but the stove was cold this morning.

I think maybe Greg was right... at least in part... with the various leaks in stove and chimney joints, the draft may just not be strong enough to pull through the coal bed reliably.

I admit I'm a little surprised I couldn't get it to work any better, in spite. The draft has always been just fine for burning wood, but clearly the demands of a coal fire are very different... and I think making a meaningful change to my setup is going to require some substantial 're-engineering'.

So my brief career as a coal burner seems to be over for the moment... but I remain intrigued, and I'll definitely be giving more thought to possible modifications... and maybe a *real* coal stove for next season.

Once again, the help here was genuinely appreciated. Even though I didn't have much success, I learned a lot from reading here on the forum.

Thanks.

Peter B.

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