Coal fire smoldering out due to poor draft...?

Hello lockeal, and welcome to the forum.

The bottom line is that coal needs a lot of air, many times more than wood from my experience.

I went from a 6" chimney last year to an 8" chimney this year, and I added about 5-6' in height. The difference has been that the boiler's combustion blower rarely comes on once the fire is stable. The added draft from the bigger and better chimney is doing the job.

If you are going to do anything to your stove, I'd add a combustion blower. They are less than $100, and really help getting a fire going and if hooked up with either an aquastat [for a boiler] or thermostat for a stove or furnace, the blower can stabilize heat output as well.

I'm sure your chimney will draw much better once the weather cools down. Cooler weather is just a few weeks away!! There is a simple check for draft in your chimney and stove: when you open the loading door, with either a wood or coal fire, do you get a roomfull of smoke and fumes?? or is there just a little smoke getting out then it is pulled up the chimney?? With my earlier too-small chimney I had smoke getting out into the room in huge quantities, now I get only a little smoke when I first open the door.

You said in your post that you had tried a lot of things with your attempts to get coal to burn. I too have struggled at times to keep a fire going or not burning out.

The main thing with coal is air flow, and heat from the coal bed. You need to have as deep a fire [pile of coal] as possible. I can get about a 12 hour burn in my firebox if I heap the coal on to a depth of at least 14-16". My fire burns about an inch an hour. If you don't have more than say 6" of coal on the fire, once it burns down to a thin or shallow fire, it starts needing more fuel, the heat in the pile will drop and the fire will go out. Leaving some unburnt coal behind. The fire needs to feed on itself. A single piece of coal usually won't burn, it needs to have heat from other coal next to it.

It is rare in my boiler to have a fire burn all the way down to just ash. If I'm letting the fire burn out, there is always some coal that would have burnt longer and more completely in a coal bed that is left behind.

Your grates need to be able to let the burnt ash fall through into the ash pan as the fire is burning. Otherwise the ash will clog the grate, block the air flow and smother your fire. If you go out and shake the grates at 3-4 hour intervals, does the fire keep going? Are you trying to get a load of coal to burn all the way to ashes like you would a wood fire??

I hope some of the above is helpfull, I wouldn't reline the chimney unless nothing else works.

Greg L

I did a search for your stove and can't find any information. Can you post a photo of the stove and the firebox/ash pan/ draft controls?? This will help us help you.

Or maybe scan a page from the owners manual of the exploded view of the parts in the stove. [assuming you have one]

Greg L

With the sliding draft slots in the ash pan door fully open, and no restrictions in the chimney flue [manual damper open] the fire goes out with still 8" or so of coal? There are not any above-the-fire air openings right? Is the loading door gasket good??

I'd check the grates for clogging. Try shaking at about 3-4 hours. Shake 'till you see hot coals fall into the pan. If it draws for 4-5 hours then dies, I think it is ash clogging the grates.

Does the blower on the back of the stove blow air around the stove cabinet and out some heat vents?? A combustion blower would have to be added so that it blows only into the ash pan area and forces air up through the coal bed from the bottom.

The sole source of air to my firebox is the 2" diameter screened opening in my combustion blower. I'm feeding a fire that is about 60-70# of coal. Almost two 5-gallon pails of coal.

When your coal bed is burning, is there anywhere in the firebox where air can get around the coal bed?? All air must go through the coal, none can be 'sneaking' around the coal. Or getting in above the coal. [this works for wood, but not coal]

I can put out my fire by raking a portion of my grate clean of coal and letting the combustion air out and around the coal bed, The fire dies in about an hour for lack of air from underneath.

Does the stove do better during the night with cooler air temps??

Greg L

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Have you tried opening a window in the room where the stove is?? If your house is really tight, you may have to provide an air duct from outside to near the bottom of the stove to provide outside air.

If your house is really tight, the chimney is trying to pull a slight vacuum on the whole house. Open a window and observe the draft, does the smoke vanish up the chimney??

Just more ideas. Greg L

Hi Lockeal, any difference with the stove's performance this last weekend with the cooler nights?

I'm thinking that a 3" duct coming up through the floor from the basement or crawlspace, venting the stove to the outdoors will make a huge difference in your stove's performance.

Greg L