Bituminous Coal Burning Erratically Because of Fluctuating Temperatures

Hey Greg - thanks for the reply. Weather out here has been 50-60 daytime and about freezing at night. Seems to make the coal burning somewhat difficult, and this is my first week trying to burn my new stove.

Seems that I can get the coal fire burning after starting a wood fire, and everything seems OK. I don't have preheated secondary air, but I do have some secondary air coming through a draft slide in the load door. Seems that this Wyoming bituminous burns pretty clean, as nobody has problems burning it with Warm Morning stoves, and they don't preheat the secondary air. Chimneys stay clean and all. 've just been leaving my secondary air wide open, which amounts to about a dozen 1/4" holes in the load door draft slide. Maybe I should close it after the volatiles burn off?

The problem I'm having is that the burn seems very erratic. The first 2 mornings, I woke up and still had a very good coal bed to work with. Now the 2 most recent mornings it was pretty much dead, and had to add wood to get going again. I tried opening the ash door for 15 mins or so, but didn't help much. Then I shook the bed, which didn't seem to do much - and reading some posts here, that may have been a mistake. Also, the fire does not seem to want to spread - If I only get about half the bed burning, it doesn't spread too well to the left or right. Maybe my bed isn't deep enough. I might have about 2-3 inches of bed depth.

Weather was way different too - a cold front had moved in and likely changed the barometric pressure quite a bit. Is that critical during early season?

BTW, the stove I'm burning was inspired by the drawings posted by Berlin on this site. I spent spring and fall building it. As soon as I can get the CAD files cleaned up, I'll post them here, along with some pics.

Still have alot to learn, but this forum is quite helpful. I find I have to be careful to remember that bituminous is not anthracite, and to be careful not to apply all anthracite advice to bituminous.

BTW - maybe this post took a turn and needs moved to the bituminous catogory?

Steinke

Hi Steinke. I would definitely close off the upper [secondary] air after the volitiles have burn off. This is probably the cause of most of the issues you described.

Without all the air going through the coal bed, the fire won't be hot enough to burn or travel across the coal bed. Any air getting past or around the coal bed can allow the fire to go out.

I'd make the coal as deep as reasonable. 2-3" is not enough. I'd like to see at least 6" of coal for an all night fire. The deeper the better. The area of the coal determines the heat output, the depth of the coal determines the length of burn. So shovel it in!!

Your ashes that remain in the firebox, are they hard and melted together, or crunchy and break up easily from the action of your grates?? You might have a build up of ash blocking your grates, this will block oxygen to the fire.

All bituminous coals have different burn/smoke/soot/and ash characteristics. Once you have yours figured out, you will really enjoy burning coal. Especially with a stove you built yourself!

I'll move this to the bitum. forum later.

Greg L

Thanks for the help. Now that you mention it, I think I had the secondary air at least mostly closed the first few days. Maybe that's the smoking gun here.

My ashes are pretty crunchy, and fall through the grates pretty well when I shake them. If I look up at the bottom of the grates through the ash door, I can see hot coals here and there.

I'll try a deeper coal bed and closing the secondary air. I'll give an update tomorrow. Thanks.

BTW - A buddy of mine has been burning the same coal in his Glacier Bay hand-fed stove for the past few days as well, with better success. He doesn't even have any secondary air, only primary. That too points to my problem being with the secondary air.

Steinke

Just to update - I closed my secondary air and the results are encouraging. The coal burned much better. I built a 6" deep bed last night and still had enough this morning to get the next grocery bag of coal going.

With the secondary air closed, I was able to get the stove thermometer to 500 degrees F, (which is of course all relative depending on where you put the thermometer, mine's at the top front above the door). That's the hottest I've had the stove so far.

Thanks for the help. Like I said, I'll post the plans for the stove as soon as I get them cleaned up and modified a little based on my first few week's experience.

Steinke

What you have there is some very good bituminous. It will probably burn much like anthracite and may even have more BTUs per pound. Some bitumins are up around 15,000 BTUs.

You are right about this bituminous. The guy at the mine said that it runs over 12,000 BTUs. There is some rock in with it, but the hand-feds are pretty forgiving of that. Not all Wyoming bituminous mines are this way. Many are well below 10,000 BTUs.

The coal I'm getting is high in BTUs, but also high in ash. Began at about 11% ash, and mine operator said it's now about 20% ash. For that reason, the stove plans (I'll post later), as well as the stove I built, has a large ash pan and ash door.

Steinke

Steinke, do you have digi-pics of your home built Coal Stove? They'd be cool to scope out in lieu of the CAD files you want to clean up ....just a suggestion.

Here are a few shots of the stove to tide you over. Some features to keep in mind given my location and situation:

I have high ash content (up to 20%), so I made the ash drawer extra large.

I patterned the stove mostly off of the Harman Mark III, but made plenty of changes.

The firebox can be reduced by removing one or more of the connecting pins on the shaker system and placing firebrick on the rear grate(s).

Body is from 1/4" steel, grates are 3/4" sucker rod and 1/2" rebar. I made a jig to weld them up. I found an old metal crisper drawer from a refridgerator for the ash pan. I need to build some hinged "wings" for the pan to funnel ash into it near the sides.

Tubes extend thru firebox and into false back where a blower is attached to help with heat transfer.

I'll give more details later, probably under a different post, but I'll give a link from this thread.

Steinke