Burning Coal In Modified Wood Stove

Hello... just found this forum.

I have an antique parlor stove that I've retrofitted for improved (wood burning) efficiency and safety. I've used it in modified form for quite a few years and am happy with its performance.

However, it has been a nasty winter here in SW Wisconsin, and my wood supply is running low. I am thinking - as an experiment - of trying to burn coal in the same stove, as a supplement to wood.

I'm just beginning to think about this, and thought I'd ask for opinions on my chances of success with the setup I have.

Already, the cast iron firebox has been lined with firebrick, there is an underfire draft (as well as a side draft), and I have replaced the original grate with a small shaker style grate. The depth of the firebrick is about 8 inches at present. I also installed an internal baffle to make the stove (effectively) a base burner, and to slow the flow of exhaust through the stove. I am able to set a wood fire to a crawl if need be, and have no problems with 'runaway' burns.

I don't as yet know what type of coal (if any) might be available locally. I'm only heating three small rooms in an older frame farmhouse, and thinking my coal use would be limited to the coldest days.

I guess my main concern at the start is whether the (underside) draft will be sufficient... and whether the shaker will be effective with coal ash... but I may be overlooking some other obvious issues.

What think any of you?

Thanks for all replies.

Peter B.

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Hi Peter, welcome to the forum. From your description, you have the main ingrediants for a coal burning stove. The only way to tell if it works well is to try it.

In your area the only local coal is bituminous, which is pretty sooty, with lots of volitiles to burn off. But it would be a lot less expensive than buying bagged coal that is trucked in from Pa.

Try to find bagged nut or pea sized coal at one of the local TSC, Farm and Fleet or fuel retailers.

If you can set your stove up so that all the air is from under the fire, up through the grates, and you can build and hold a deep fire, you should be successfull with anthracite. Bituminous would work too, but will require a bit more work. Read up on the bituminous characteristics on the Bituminous forum.


Post some photos of your stove, the firebox/grate/ashpan , this will help us help you.


Welcome, Greg L

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Greg:

Thanks much for your reply... I'm encouraged to give the stove a try.

Obviously, my next step is to try and find a local supply of coal, which I'll do as soon as I'm off my dialup connection.

I'm not very skilled with a digital camera, and the stove is in use all day, so photos may not come for a while.

Last question for the moment: the underside draft is through the grate, which is only about a 4 inch diameter, while the firebox floor is about 8 to 10 inches in diameter. I'm wondering if draft air will diffuse to the sides of the coal fire or whether I'll want to cluster the coal immediately around the grate... as possible.

If I can find the coal and the trial is anything like a success, I can always further modify the stove... in fact, I've got some more firebrick splits upstairs that I could use to reduce the diameter of the firebox floor.

This might be a fun experiment... but we've got (another) 5 to 10 inches of snow forecast for tonight and tomorrow, so even if I find coal, I won't be able to get out to get it for a few days (sigh).

When I can, I'll make a report.

Thanks again.

Peter B.

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Hi Peter, it would be better if the whole floor of the firebox was a moveable/shaker grate, but by no means an absolute necessity. I'd burn it the way it is and see how well it does.

With anthracite, It likes a hot fire as a base to start on. And all the air has to come up through the coal bed.. So get a good hot bed of wood coals, several inches deep, and add several inches of coal over the whole surface of the fire. close the loading door, and let the under fire draft feed the fire air from below... you will hear a lot of snapping, crackling, like 'rice crispies' breakfast cereal.. This is the pieces of coal cracking from the heat... Then you will start to have blue flames dancing above the fresh coal, and soon a red glow from below..

Once you have the coal fire established, then fill the firebox up to the top of the firebrick... Coal fires burn from the bottom up and the amount of heat is determined by the area of the fire, The duration of burn is determined by the depth of the fire, and how much air you feed it. So a small diameter fire that is really deep will put out a moderate/small amount of heat for a long time... A wide shallow bed of coal will make a lot of heat for a short period of time.

Any luck with finding Anthracite in bags?? Or local Bituminous?? You might try PM'ing some of the Wisconsin and Illinois coal burners to find coal suppliers... Or look at the coal suppliers thread at the top of the list of forums on the home page.

Greg L

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LsFarm wrote:
Any luck with finding Anthracite in bags?? Or local Bituminous?? You might try PM'ing some of the Wisconsin and Illinois coal burners to find coal suppliers... Or look at the coal suppliers thread at the top of the list of forums on the home page.

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Greg:

No luck at all so far with 'likely' local suppliers... this part of Wisconsin seems to have gone to oil, gas and propane fuels *only* for residential use.

About to call a local blacksmith and a local farrier... see where they get theirs, and maybe buy a single bag. Any idea how blacksmith coal differs from heating coal?

Thanks for the advice on basics.

Peter B.

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Blacksmith coal is high quality Bituminous... I think. Not totally sure. I'm sure it's not anthracite. Did you look on the last few pages of the 'where to find coal' thread?? There are a few forum members from N Illinois and SE Wisconsin...

Greg L

LsFarm wrote:Blacksmith coal is high quality Bituminous... I think.

This is what most will use, charcoal too and sometimes coke. You would need a different type of forge than what is used by smiths for anthracite. They typically have a metal bowl with sand in it, just blow air at it with a bellows when you need the heat. Toss a lump in now and then to keep it going. Anthracite would require sides and a bottom draft.

Well, durn it...

After a day on and off the phone and the web, I never turned up a single lump of coal in SW Wisconsin - no bulk, no bagged.

It looks like the (northern) Illinois and Wisconsin posters here are both buying bagged coal from a stove dealer in Rockford, Illinois... a fair hike from here, but maybe a possibility in the future. There's a Reading dealer further up north in Wisconsin, but that's not much help right now either.

Probably the best suggestion I got all day also gave me a laugh. There's a heating plant in Madison (not far from where I work part time - when weather permits) that keeps a huge (unfenced) mound of coal on hand for their own winter use... and sometimes there's an accidental 'overflow' from the pile. Maybe I could bring some burlap or plastic bags and offer to clean up for them now and then... if I can even find the coal under the snow.

I guess I won't be able to make the trial anytime soon... and it looks like I wouldn't be able to count on a convenient, economical source for coal even if the trial was successful.

But my curiosity is up, and being able to hold a fire for more than eight hours or so sounds pretty good to me right now. Maybe before next winter, I'll get a few bags to keep on hand for the worst weather.

If anyone in my area happens to be 'listening in' and knows of a good coal source, I'd sure like to know about it.

Thanks.

Peter B.

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With a tip from another Wisconsin forum member, I've located a source for bagged anthracite in my area.

It will be another couple/few days before I can get out from under the latest heavy snow, buy a bag or two and make a trial burn, but for what it's worth, I'll post pack with details.

If all goes well, coal may just save my b*tt this season.

Thanks for this forum.

Peter B.

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Brought home a bag of Blaschak nut today, and started very slowly off a bed of wood coals.

Disappointed at first with low heat output, and kept nudging up the quantity of nut - very conservatively - til I could actually feel the stove throwing a bit of warmth. Meanwhile stack temp was way below what I'm used to for a decent wood fire... and I moved the probe down to the top level of the stove... where it's settled for now at 600.

Don't want to push things yet... still working with a very shallow coal bed, and will likely wait til tomorrow morning to 'see what I've got' - i.e. did anything internal melt down... and do I still have a coal to light off another wood fire?

Thinking I'll rotate wood and coal til I have a better handle on coal burn characteristics... coal appears to be a whole different 'philosophy' at this point... and I'm glad as h*ll I didn't load up quickly.

Bagged prices are surprisingly good at the dealer I found... and they even had a couple of Round Oak wood stoves on display... one with a crack in the cast firebox from burning coal without a firebrick surround.

Here's a pic of my stove if it was restored properly... but keep in mind, instead of 'nickling' and diming it to death, I modified it internally so I might be able to hold a wood fire for more than 6 hours... or burn coal without the factory hopper (NLA).

In short, so far so good.

Thanks for the help I've gotten here.

Peter B.

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You'll have to "dampen it down" for overnight, but I'm sure you did that with the wood as well.

If it sounded like I was 'crowing' in my last post, I'm eating crow now.

My first test was begun with an absolutely clean grate, and went reasonably well until I made the mistake of shutting the lower draft completely before going to bed. The fire went out within a few hours, leaving a mess of ash and unburnt coal.

I (mostly) cleaned out the stove next morning and tried again, but the grate now wants to jam and clog... and I just can't seem to keep an adequate underfire draft.

So... until I can figure out an improved grate arrangement, I'll have to leave the all-coal trials alone.

I'm wondering if there's any 'theoretical' value (other than maybe extending the burn time) in adding coal to the wood fire as a supplement?

I'm likely to give it a try in any event, just to see what happens, but reading what I've found so far suggests the coal will simply not burn efficiently.

I'm disappointed, of course... I thought the grate would work, but I hadn't anticipated the effect of small coal chips fouling the grate, holding ash and preventing decent shake down.

Oh, well.

Thanks.

Peter B.

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Had you not totally closed the under fire draft, the coal might have burned completely, ... to ash and not have caused the problem with the grate fowling. It deserves another try with some burn modifications. .. maybe, even a different size coal. IMHO

Dallas:

Thanks... that had crossed my mind too, but I was so frustrated by the end of the day yesterday, I wanted to chuck the whole business.

It's going to be fiercely cold here tonight and tomorrow so I can't 'afford' another failed trial, but I'll definitely give it another shot with a clean grate when I can, as everything but the clogging seems to be okay - no high drama or meltdowns.

I'll make another report following the next test.

Peter B.

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One thing to keep in mind is, that wood responds much quicker, than does coal, to changes. In other words, you can open the draft and have a roaring wood fire in no time, whereas with coal, it is much more subtle. The same happens when going the other way .. a wood fire can burn up or die down pretty quickly compared to a coal fire. A change to a wood fire stove will be evident in minutes, whereas a coal fire won't let you know what is going to happen for quite some time. That's why it takes practice, patience and understanding, ... plus trial and error. ... sounds like "parenting" .