I was wondering what the structural differences were between coal and wood stoves. Is there a reason you can't use coal in a wood stove, or visa versa? Thanks.

-- Amy Leone (aleone@amp.com), September 03, 1998

Answers

Amy, I have used both. The major difference between the two is the addition of a 'shaker grate' in the bottom of the stove along with a clean out door underneath it.

Wood does not care where it gets it's air from. It will burn with a draft from the top of the fire. It burns better with a controlled draft from the bottom or side, but it will still burn. Coal MUST have a draft from underneath the coal bed. The grate is there to support the bed of burning coal so air can enter from underneath, and it shakes so the coal ash can be shaken down into the bottom of the stove for removal.

We get about 80% of our winter heat from a small coal stove in the basement. If we carefully control the air flow we can keep the stove going for weeks at a time without ever letting it go out. Shake it down, refill with fresh coal, clean out the ash.....twice a day with ours. Care must be taken with the hot ashes which can have live coals in it.

Stoves can be had that burn both wood and coal. That's good and bad. One feature of a true coal stove is the depth of the fire bed. A long burning and efficient coal bed must be deep. Ours is about 14 inches from grate to top of the fire brick. A full load of coal is about 40 pounds. Wood stoves usually don't have such a deep and narrow bed. They don't need it.

A coal stove will burn chunk wood just fine. It won't burn as long as the coal would, but it will work without a problem. A wood stove will almost never burn coal correctly. Even if the wood stove happens to have a shaker grate (many high line ones do) the grate will usually be too course to support a coal bed.

Another difference: Wood stoves will build creasote in a chimney unless carefully managed. If it gets regular maintenance and is run at a decent tempurature that's not a huge problem. Let a lot of creasote build up in a chimney and you risk a runaway chimney fire and possible severe damage. I have had this happen. I put mine out by setting a BIG pot of water on the fire and closing my fireplace doors. The combination of steam and lack of air shut the fire down.

After a good friend (an accountant) died I used to go over and maintain the wood stove for his wife. I would sit in front of the stove and shovel in IRS forms to get a good roaring fire going and burn out the chimney. Lots of satisfaction in that. Jon would have enjoyed it.

Tip on running a stove, either coal or wood: Leave a layer of dead ash at the bottom to insulate the stove from the worst of the heat. It will greatly enhance the life of the stove. The grates can take high heat, but not forever. They will eventually warp or crack.

No matter which kind you get, buy a chimney thermometer and use it. Get a magnetic one and learn where on the stack it gets the best reading. Usually close to the stove. You should also consider an automatic self adjusting flue vent. It will react to stack air flow and compensate for exterior wind conditions. In high wind conditions I have seen our stack flue go wide open and STILL have the stove get way too hot. If a high wind comes up it can literally suck the exhaust up your chimney and turn your nice calm stove into a blast furnace.

Hope some of this helps.

-- Art Welling (artw@lancnews.infi.net), September 03, 1998.

One additional point about the wood stove versus coal stove debate. It's not a good idea -- a very bad idea in fact -- to burn coal in a sheet-steel stove. The steel can't take the higher heat and will eventually warp and even burn through. The sides of the stove can heat cherry red if coal is burned in it. Cast iron is preferable, IMHO. I've seen airtight steel stoves that have been used to burn coal or coal and wood mixed -- the area around the stove collar, especially, is often warped and weakened.

-- J.D. Clark (yankeejdc@aol.com), September 03, 1998.

Watch out if the insert/stove protrudes into the room: kiddy fingers and hot stoves don't mix. Its not just toddlers, but accidental touch/brushing/falls/trips too. My sister (3 small ones) put a fence-type barrier around hers, but her stove was in the middle of the room. My brother had no problem with a wood-burning insert that pretty much just covered the fireplace.

Don't be paranoid about safety, now, just remember that the modern conveniences were built specifically to give you warm air with a maximum of safety and a minimum of effort.

My own chimney is dirty, thank you for reminder on chimney sweeping.

-- Robert A. Cook, P.E. (cook.r@csaatl.com), September 04, 1998.