# Converting a coal stove to wood burning



## WoodBerner (Oct 9, 2019)

I had another thread where I was discussing burning wood in my antique Bonny Oak coal stove. The consensus, and to some degree my experience, is that the stove is pretty inefficient with wood. It would appear that the stove is not very air tight, and the bottom grill is really intended for coal which requires more air.

My thought is, how difficult would it be to modify the stove to be more efficient burning wood? It would seem the primary two objectives are sealing off the areas where air is being drawn in, and putting something over the grate to make it more solid.

Has anyone tried this? I couldn’t find anything in the search, and I’m most curious about what I could use on top of the grate.


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## ct01r (Oct 11, 2019)

I have a Mountain Oak stove similar to yours that I sent to a guy to have it commercially rebuilt.  They're made to use primarily coal, and simply have too many small gaps that add up to a fair amount of in-leakage to be used efficiently with wood.  (Compared to a modern wood stove.)

That being said, if you're just using it to supplement your central heating system, you might be happy with it.  I had a 2 hour burn time with the Mountain Oak with soft (Norway) maple when I got it back from the refinisher.  Now I can go 4 hours.  I'm shooting for 5.  You probably have a space on the side for an arm to go into your grate to shake the coals down.  I sealed that off by taking the arm out and stuffing the hole with the widest gasket material I could find.  I also used thin gasket material where the doors close, but that actually caused a bigger gap because now the door isn't tight by the hinge.  I'll continue to fine tune it, and I'm pretty confident about getting to 5 hours.  When I use better wood (hickory, white oak), I hope to have 6-7 hours.  Good luck!

Oh, about the grate: I've been told by 3 different guys that rebuild parlor stoves, that the difference in grates is the openings in them.  Wood grates have smaller openings so the embers don't fall through; that'll hold the heat better, and give you more time between reloads.  I'm not sure I agree.  I had an extra grate the guy gave me when I got mine refinished.  I used it for a month or two, then tried it without.  I get more burn time by using the original coal grate because there's more room to hold more wood.  I'd say just try it with your existing grate, while shopping on eBay, craigslist, etc. for an old stove cheap for just the grate. If you know a welder, he might be able to make something up cheap.  Sorry this is so long.  Curt


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## bholler (Oct 11, 2019)

If you are going to shop for anything shop for a wood stove


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## coaly (Oct 11, 2019)

WoodBerner said:


> I had another thread where I was discussing burning wood in my antique Bonny Oak coal stove. The consensus, and to some degree my experience, is that the stove is pretty inefficient with wood. It would appear that the stove is not very air tight, and the bottom grill is really intended for coal which requires more air.
> 
> My thought is, how difficult would it be to modify the stove to be more efficient burning wood? It would seem the primary two objectives are sealing off the areas where air is being drawn in, and putting something over the grate to make it more solid.
> 
> Has anyone tried this? I couldn’t find anything in the search, and I’m most curious about what I could use on top of the grate.



Correct, firebrick is easiest (if you have room for 1 1/4 thickness) or steel plate in the place of grate, and close pipe damper enough to prevent air rushing in all the leaks as well as trying to seal them up.
"Rutland Stove and Gasket Cement" is your friend.

The problem with solid bottom will be letting it go out constantly to clean ash.
A square larger stove burns down to fine ash behind the air intake overnight. Remove a little ash from the front each morning and rake coals and charcoal from rear ahead with a little ash. Build the new fire on the coal bed. It will take right off. This prevents the need for letting it go out to clean ash. That's one of the advantages of an older Fisher type, along with larger cooktop, no door gasket seals, very fixable steel plate. A rectangular or box type stove is also shaped to fit wood better. You want logs laying horizontal, not vertical that the heat travels up them igniting them quicker. Any stove you get involved with should be firebrick lined. It also radiates heat back into the firebox creating higher temperature which burns cleaner.

Wood should be burned on 1 inch of ash. The best grate system I've found is on Amish built kitchen ranges. It is 1/2 inch rod or rebar. Weld together with a few cross ties so they are spaced exactly 1/4 inch apart. This loads up with ash to block airflow so you're burning on an ash bed, or rake across it to dump it through the slots into ash pan area below. It will burn faster until the ash builds up, so be careful how much you remove.
More than 1/4 inch falls through and doesn't build up, less blocks up and is difficult to dump.

I have converted a few steam boilers to burn wood with good results, but it takes practice to learn what it takes to get the results you need. They were road type boilers that tend to shake themselves with movement, so they need very little attention. (and tighter than 1/4 inch) Stationary (like a stove) needs more babysitting, but you don't want to over-clean, down to holes in the ash bed.

Too bad you're not in PA. I have an assortment you could choose from to trade for your antique.


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