Cold Chimney?

I suspect my chimney is causing problems with my Harman Magnafire Mark I which I installed last November, I switched to coal from wood. I have a lot of problems with burn time, it seems the fire will go out in a matter of minutes if I let it get too low. The problem has gotten worse over the past few weeks, but I suspect it's coal with a high iron content. Today the stove burned well with coal that I had shoveled off of the pile a few weeks ago. As soon as I added coal from a pail that I just filled, I started to lose the fire. Got it back with the rest of the coal from the first pail. I'm going to try some from a different dealer. Until then-It's either sweat or freeze in NJ!
Thanks!

Sorry, I forgot to mention that the draft readings run from 0.6 to 1.5 WC with a full fire burning. Thanks.

I fear that coal heat may be corrupting the cats of America. Yet another non-productive cat is seen in the photo above basking in the glow of a coal burner.

Yes, it's true. Actually it's 2 cats and 2 dogs that sleep by the stove. The child in the highchair is a doll, by the way. We don't leave the kid next to the stove! Soon I'll get to the stonework behind/under the stove.

WoodnCoal, sounds like you are trying to 'wean' your stove. A coal fire will go out with good draft, good coal and in a good stove if the level of coal is too low.

This is my theory: each piece of coal seems to need he heat of the adjacent pieces of burning coal. Each piece feeds off it's adjacent neighboring pieces of coal. Without the heat of the entire bed of coal the fire goes out. A thin layer of coal can't support itself.

So, try loading your Mark 1 up to the top of of the firebrick, it will burn much better, even poor coal will burn much better in a deep fire.

Hope this helps

Greg L

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Thanks for your reply, Greg. I have been filling the stove to the top of the firebrick. When I first got the stove, I'd load it up before bed, and in the morning it was still burning. Lately it's completely out in the morning. It's doing well now, I'm going to load it up again soon. I also have had problems with ash build-up at the bottom elbow of the stovepipe, I have to clean it out every 2 weeks or less, as soon as I start having problems maintaining the fire. My stovepipe temp. usually runs around 300 degrees.
Thanks again.

Wood'nCoal wrote:Sorry, I forgot to mention that the draft readings run from 0.6 to 1.5 WC with a full fire burning. Thanks.

You need a barometric damper for starters, .06 is the maximum draft for coal. Anything higher, your heat is going up the chimney with your coal. Like the others said, you need a deep bed of coal. You have to avoid smothering the fire too when loading fresh coal. Before you shake, rev the fire up by opening the draft damper a few minutes. This gets the bed hot enough so you can play with it. I have a thermometer on the stovepipe, and I like to see about 100-150* rise in stack temp before I shake. After shaking, I bank the coal with a small hoe by pulling some of the coals toward the door leaving a depression in the rear. Then I fill the depression with the fresh coal. Anthracite needs to be burning all the way through the bed to the top. If you just pour coal all over the top of the old fire it will tend to smother it.

OK, next idea: is the entire bed of coal burning evenly? Or is one end or the edges or a corner dark and burning slower??

Several Harman owners have reported ash building up on the grates enough to block air flow to the coal.

If you look up at the bottom of the grates through the ashpan door, is the red glow of the coal bed even all the way across the grates? If not shake the grates a little more aggresivly, or make a small poker from stiff wire, I recommend wire about 3/16" diameter. Bend a 4" 90* end on the wire and use this tool to poke through the gaps in the grate where the coal appears dark. Usually you will get a shower of ash once the blocking pieces of ash are dislodged. Once the air passageway is open the coal will start burning.

If this isn't the problem either, then it quite probably is the coal. The only way to eliminate the coal as the problem would be to swap completely over to a different coal source.

Is the ash from the 'bad' coal different from the ash from your usual coal.?

Hope this helps

Greg L.

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I have a new Barometric Damper from my oil furnace, I thought about installing it on the Harmon, but I've been too caught up in the cold chimney theory, I figured the damper would only add to the problem. Another thing-if I have a hot fire burning and cut the draft down too low I begin to smell combustion gases from around the pipe. It clears up when I open the draft up. So before I go completely off of the deep end...I'll install the baro damper and set it at .06 WC. Thanks for your advice regarding banking the coals. I do that, but not every time, I will make sure to bank the coals everytime.
Thanks for all your help.

Greg,
The situation you describe are very familiar. Yes, I do tend to have an uneven fire, usually one area is hotter then others, when I shake the coal I can usually get a fairly even glow through the grates. Sometimes I have to shake it a lot to get it cleared out, and at that point I start having problems with clinkers or pieces of unburned coal jamming between the 2 grates. I have also suspected that the ash build-up is affecting the draft, even with thorough shaking. The first ton was nut and the ton I'm just finishing is stove sized. I've pulled unburned pieces out approx. 3" in dia. that have a pock-marked appearance, sometimes with a very hard brown unburned center. Today I pulled out a partly burned chunk that actually had a red coloring (Iron?). I'm going to pick up a few bags from another dealer this week. I will try your wire suggestion.
Thanks!

I ran about half a ton stove through my boiler just recently and noticed that the grates plugged with crap at twice the rate of nut. Sure burned hotter, it spit out two more firebrick.

I thought the stove size would give me a longer burn, since it was larger. It seems I had better results with nut size, that's what I'm going back to.
I'll keep you posted. Thanks everyone.

That's what I used to think, but the old codgers (well, older than me) always said "hotter and faster" and I found that to be true. My little boiler didn't have any trouble keeping up when it was bitter cold. It would have if I had been running nut. From now on I'll keep some stove handy. However, I also noticed the grates loaded with crap faster and it loaded up with ash at a higher rate. So there is a tradeoff. My boiler is much happier with the nut, but each firepot design and size has it's favorite size coal.

put a T in the bottom elbow, with a end cap you can take off to clean out easily.

Berlin,
I had the same idea regarding the tee w/ cap. My local dealer didn't have it in stock, they ordered it for me. I also will install another tee for my Baro damper, I'll give that a try too.
Today a bought 80 lbs. of nut coal from another dealer. I know where this coal was produced. I cleaned out the stove completely, now I'm waiting for the coal weather to try it out. It should be cold again by Friday, today it was 70 degrees here in Sussex County, NJ.
I started the stove last night, but I never got the fire hot, and it went out.
Today when I emptied it I found lots of unburned coal and an interesting clinker which is pictured below. I've found these quite a few times with the ton I'm just finishing. It is some sort of metal, I'm not sure what it is. It's not magnetic, though. It is quite hard and feels heavy.
Greg: I made up a wire poker as you suggested and it works great to get the ash, etc. out of the grate openings.
Thanks to all for your help.