Coal stove, burning wood, and chimney fire(s)

Almost has to be...assuming there is not a huge air leak somewhere...can you cut the air off and starve the fire?

 

yes, if I shut it down the fire dies out moderately in the box, the top air knobs are designed to allow air in. The chimney fire goes it immediately.

 

Sounds like that stove really is just a coal burner.
I would think that since you can cut the air off enough to starve the fire then you still should be able to burn wood if you just open the controls less...I dunno, seems logical to me. I'd still send 'er packin ASAP though. A modern EPA type stove will be much more efficient.

 

Just remember, all the old timers and the prevailing school of thought was "you can't/shouldn't burn pine in a woodstove. You fine folks here have taught me that is true. I'm burning some Hemlock now. A lot of those folks cut Oak in the winter and burned it in the same year 6 to 9 months later.

 

Fixed it for ya'.

 

You're burning the smoke in the pipe and chimney creating a secondary combustion chamber.
It can happen if there is a leak into the connector pipe at the stove connection, or you're leaving too much air into the top intake. When smoke particles light off in the connector pipe due to a leak, you get a glow in one spot above the leak. That of course will light off any small creosote accumulation.
The top intake should only be cracked slightly. More than that allows cool inside air up the chimney bypassing the fire. Remember the lowest pressure area in the system is at the flue collar, which is why atmospheric air pressure pushes into the stove filling the void or low pressure area created by the chimney. The upper intakes are for coal gas ignition to get oxygen to the top of the fire. The old guys that thought the world was flat knew opening them (or cracking a stove top lid) cooled the flue to prolong a coal fire overnight like a barometric damper. Too much allows atmospheric pressure into the top, equalizing the pressure in the stove, instead of forcing air up through the fire bed to ignite coal. So the fire slows. That's fine with coal. You can't do that with wood since wood doesn't care where the air comes from, so it uses a portion of the upper air supporting combustion. Any excess air left into the top cools the flue accumulating creosote rapidly. If flue temperatures are hot enough with smoke present, you get ignition. It will burn smoke free in the chimney and you may see a glow from the refection under the cap when clean.
The reason you will not get a long burn on the grate with wood is no turbulence in the firebox. Air enters under the fire, rises directly up without mixing well with the flammable gasses escaping from the logs. The air only changes direction a few times getting through the logs.

A coal fire depletes the oxygen coming up through the fire bed, so to get the coal gas escaping from the heating coal to ignite, which is the blue flames on top, it needs a small amount of oxygen from secondary upper intake. Some coal stoves have bypass slots in front of grate for oxygen to get to the top of fire (Gibraltar) and European stoves use slats for glass instead of a solid glass so they leak a slight amount between the panels to get oxygen to the top. You can see by that design how very little is needed. Yours should have slots or air space in front of grate or banking plate for a small amount of air wash to keep fly ash off the glass. (the glass should still be wiped daily with a damp rag during coal use) It is not designed to keep wood smoke from contacting glass. A stove designed for coal with the capability of burning wood normally has a second vented banking plate like a fireplace grate installed for wood burning in front, instead of the solid coal banking plate. They will not be as efficient as a stove designed for wood burning on a bed of ash.
For coal use, this should have a barometric damper to set constant flow through coal bed. Do not use with wood with barometric damper installed.
Your stove also looses the UL rating burning fuels other than coal. An exception is made for starting only with wood.

 

Pay attention to Coaly and only burn really dry wood not half or quarter dry stuff unless you like the jet engine in your flue(burning wood gas).

 

Coaly, thanks for the info. I figured that's what I was doing and what was going on but I never put it together with the air over the fire knobs. They are designed to leak as they do not close all the way. I do not run a baro as I like burning wood too and the stove is a pia to get behind to jam it closed when burning wood. Today I will probably start coal, but prior to that I will take your advice and close up the air over the fire knobs and see how that goes. The other thing I did check was the temps of the door versus the stove top, it's almost a 200*F difference, so when I'm at 500/600 door I'm about 700 to 800 stove top.

The banking plate is interesting, as I obviously have the solid type; I can easily fab something with slats if it works. What effect will this have on my wood fire?

Why am I feeding this thing wood every hour? Unless I am feeding it a healthy amount of air I am smoking out the chimney.

 

That's too hot and the same reason you're feeding it so often. The burn rate is too fast.
Obviously that's where it burns clean.
Without making the firebox more compatible with wood it's probably going to smoke.
To make it a better wood burner; #1, baffle to roll the smoke back into fire and manual damper to slow draft. A coal stove uses tons of air. They are designed for a huge amount of flow. You need little flow but fast moving and turbulent that changes direction and swirls to get oxygen to mix with gasses. The only way charcoal burns is when an oxygen molecule wanders onto the surface in an oxygen depleted atmosphere such as a slow burning wood stove. You've got a blast of oxygen hitting the wood, so are left with no charcoal to prolong the fire. Your air flow is probably lifting most of the ash that falls off as it burns down into fly ash up the chimney too.
If you were to lay firebrick over the grates with a slot down the middle, do away with the banking plate, (that funnels all the air up through grates) you only need a guard to protect glass. It's still going to soot the glass nasty. Then undo all that to burn coal.

I have one chimney with a Hitzer coal burner and one chimney for wood. They both have benefits and draw backs. The wood stove is in the middle of kitchen, has an oven and 24 gallon stainless water reservoir. It heats up to 3000 sf and my wife would rather cook on it instead of a commercial Garland gas range. I also added a thermostat on it. I have enough property to fuel with wood and until going to a Kitchen Queen, I liked the ease and steady heat output of coal better.

 

I had to check the kitchen queen you mentioned, those look awesome. I've never seen anything like it, although my dad used to talk about something similar that burned coal that his uncle used to run his pizza shop with in Brooklyn.
I just threw coal in yesterday, I too love the even heat and long burn times. I almost bought a Hitzer insert when I bought the Baker, it almost became a coin toss, but the Baker won out because the whole unit sits outside the fireplace fire box. I do hate the ash, dust, cost of coal. your right on the trade offs, nothing's "free".

so I shut down the over the air fire knobs, much more control, logs burned an extra hour, still crapy, also smokes like, well a smoke dragon, and yea the glass instantly soots up. without any mods this is it I guess.

guys thanks for all your input, no more chimney after burners.

 

I went with the Hitzer for the hopper feed. Heated with a front loaded Gibraltar for years, then put a log set in a customers fireplace and they gave me their old Surdiac. Those European stoves have more delicate parts, but the capillary tube controlled thermostats work better than American bi-metallic thermostats. It was a little more efficient with a heat exchanger on the back, but it had bolt on clean outs to clean the fly ash from the back every year (reminds me of a VW Beetle exhaust system) and had more parts to leak or rust away. It cleaned with a slicer knife instead of movable shaker grates. Ash leaked out as you "sawed" across the grate through little doors with hinged cover plates....... Hitzer is hands down the best coal stove I've used. (Including a Fisher Coal Bear!) If you give any coal stove a little shake to drop some ash, then open the air in the morning, wait until it's drafting and kicking up before removing ash pan. The vacuum into the ash pan area should prevent most fly ash from becoming airborne in the house. I have a double door system into a mud room on the back of the house so I can step into the closed mud room before opening outside door getting a gust of wind driving the fine ash back into the house. Coal brands from different breakers will contain more ash than others, you have to experiment until you find what works best. My Hitzer does not like Blaschak. (ironically the brand sold by the local Hitzer dealer) I get a lot more ash and it eats up stainless chimney tops.
Do you use loose coal from a bin or bagged?

Something else that can make a mess is closing the upper air intake too far before opening door to load. You can starve most stoves of oxygen above the fire and get a build up of coal gas that doesn't ignite above the coal bed. Opening door gives it the oxygen it needs to violently ignite blowing a cloud of ash at you with the minor explosion. That's the reason for the upper intakes not closing completely. The Hitzer can be fed a bucket into the hopper and closed to let heat up a while and coal gas seeps up into the hopper above the fresh coal. It's not normal to open the hopper door an hour or so after loading, but if you go to top it off for the night, cracking the hopper door on top allows a rush of air in to mix with the 100% coal gas and you can get quite a blue poof out of the hopper ! Coal fines and preheated "green" coal is nothing to play around with and is highly volatile ! On steam locomotives it's common practice to wet the coal when firing hard to prevent rapid out gassing.

 

I buy kimmel in 50#bags for 290$ ton. they are typically wet which is great, keeps the dust down, however I have over 3 tons left from last year and they are all dry, I guess I can wet them down if I wasn't always in a time crunch. I used reading in 40# bags, about 1/2 ton worth, I like the kimmel better. my first year burning, I read about stove back puffs, thought I couldn't have one with my secondary air, then one day waaa bam, puff back, pretty cool looking blue gas, scared the s$&t out of me, wife, 2 kids. ash leaked out of the bottom vents and didn't cause too much of a mess. what caused a huge mess was when the air filter on my shop vac fell off and I had no idea until I heard my wife yelling, I had blown coal ash all over the living room and kitchen....yea, I now always check the filter, what a mess that was. I have learned to stoke the fire, add coal in a thin layer on top, shut the intakes down, shake, settle ash, open intakes, refill and deal with the ash. seems to work the best for my set up. I've tried a few methods for dumping ash, haven't gotten that down yet though. I tried it under vacuum, in the open and upwind, small grocery bags and vacuum...under vacuum works great but clogs the filter quick. I watched a guy online use a grocery bag and shop vac, his ash pan looked like a dust pan without the handle, his methods was great, no ash anywhere. my ash pan is box like and large so cutting off the back will likely cause structural issues so I have to turn it upside down and bang on it to empty, dust goes everywhere. whatever, the heat is fantastic.

 

You're doing this outside....right?

 

lol, yes, and away from house and cars. I throw a lid on the can to minimize the cloud.

 

Kinda like a mushroom cloud....ain't it?
I try to stay upwind when I dump ours.