cavity in coal bed

Yesterday my stove developed a cavity under the coal bed when I shaked the ashes out . I was able to maintain the fire but but had to poke it from above to get the coal to drop down on the grate. Was causes this? Coal too ig or too small. The stove pot is a rectangle not round and the sides are strait. I think the shape of the pot may be half thee problem. Any thoughts appreciated.

Sorry about the spelling . Got posted before I could proof read.

Hey again...
my first guess would be the rough lining with the "bubbly surface" due to the fused ashes...
your fuel can´t just slide down once there´s a cavity after the ashes dropped through the grates. What you describe sounds like the phenomenon GODIN owners encounter from time to time - maybe you´ll find something useful if you take a look at one of the "petit godin" threads?
Enjoy your sunday
Mark

Search the forum for the word bridging. When I burn the fire hot, I often have to poke around the edges of the firebox to break up the bridging. It seems that where the fire is the hottest, the burning anthracite coal either expands a little like some bituminous does or the anthracite fuses a little at the hottest zone of the burn. Just thinking . . .

I see the same thing in my Harman during the really hot burns. I watch for it and change my reloading process if I do see bridging. Instead of shaking the stove first and then adding coal, I add coal and then shake the grates. Normally I don't wait around for the new coal to catch because I know that the coal bed is strong but when I see the bridging I DO wait until the new coal has caught before I shake the grates. If I don't switch it around like that I could lose the entire middle of my coal bed and I hate that when it happens! Lisa

Thanks all. I thought the sides being rough had at least something to do with it. Also maybe not getting enough ashes out before adding coal. In this stove (the Wiggisthal) it's tough to get to the ashes stuck in the corners at the sides of the grate. There is an upper clean out door but if I open that the coals once they drop would end out on the floor , not good. I think I need to try some pea in this stove. Maybe would help

I had bridging last night in my Baseburner. i think this only happens when you burn HOT for extended periods of time like the others described. When this happens on my stove, I can't even use the shaker because the grates aren't touching anything. I have to poke the top of the fire to make the ashes fall down to the grates. Then I shake it. But by the time I realize this has happened there is so little burning coal in there that I end up adding charcoal to help get going again.
I am going to try not running too hot anymore unless I absolutely need to.
If you need to run hot, just make sure you shake down and add coal more often (every 6-8 hrs if you are running really hot). That will help to reduce the chance of clinkers and bridging.
-Steve

My stove wasn't running hot. Actualy it would have been running on the cools side when this happened. I think I need to just do a better job in cleaning out the ashes and using the right size coal.

See that, ya solved your own problem.

My fire box has a "V" shape and tends to bridge quite often. Mainly when I burn it kinda hard and hot. I've seen it to the point where after I shake, I'll look in at the coal bed and I can see a huge hollow cavern thru small openings in the bridge over the top of it. It actually looks pretty cool. I should try to get a picture of it sometime ....

I'll just pound it down and shake it again

Lightning wrote:My fire box has a "V" shape and tends to bridge quite often. Mainly when I burn it kinda hard and hot. I've seen it to the point where after I shake, I'll look in at the coal bed and I can see a huge hollow cavern thru small openings in the bridge over the top of it. It actually looks pretty cool. I should try to get a picture of it sometime ....

I'll just pound it down and shake it again

My fire box has the same v shape and i get bridging also.I shake down, then take the l shaped poker and push the ash on the v sloped bricks to the bottom, then push the bridging down and reload.