rychw wrote:I have had two explosions this week thus far so I'm lowering my ash dump temperature to 105 from 110. Both times the ash was being dumped when the fan stopped. My hope is that there will be more hot coal in the fire tube that will consume the coal gas produced during ash dump. Again, for those that haven't been following this thread, I have great draft, short horizontal stove pipe run, ample available air and good qaulity coal. I'll keep everyone posted.
How would you describe your fire bed?
Higher positioned or lower?
Hot coals, thick or thin?
105* setting should get it pretty thin and very high, I think?
I came across this excellent description of how the fire bed responds to adjustments, thanks *mikeandgerry*
It is for the A-A so the ashing linkage adjustment isn't like the AHS, but the theory is all the same.
mikeandgerry wrote:The number of clicks (actually referred to as "teeth taken" in the manual) merely determines how fast the fire builds in the fire pot. Recall that on the AA M-130 the firepot is an 11" diameter open tube filled with coal from the top, burned in the middle and ashed on the bottom. The tube is open on the bottom and the ash is the base of the column. The grate on the bottom reciprocates (called "shake" in the manual), clears the fine ash from the burning coal, and pushes the ash and semi-burnt coal into an ash bin and thus allows coal to feed from the top by gravity. Shake cannot occur without the addition of new coal, whether it's needed or not. Small amounts of coal can and will be fed by gravity as a result of fuel consumption with or without a call for shake.
The fire's "thickness" or depth in the pot (which is not observable) is controlled by the temperature setting on the anthrastat. A lower ash temperature setting (120degF) stops the action of the reciprocating grate sooner resulting in a "thinner" fire yielding less average btu output for summer operation while a higher ash temperature setting (140degF) yields a "thicker" average fire with a greater average btu output for winter operation.
The shake adjuster (a small L shaped slide on the grate lever) can be moved left or right to adjust the rate at which the reciprocating grate is cycled (what you guys are referring to as ashing). Moving this adjustor left or right from one tooth (far left) to three teeth (far right) only changes the speed at which the fire shakes the coal and builds the fire. Only the heaviest loads require three teeth. The anthrastat, along with the load on the boiler, controls the rate of burn and the amount of ash generation. Under low loads, the unit will eject considerable semi-burnt coal because the fire will die down very low and have to be rebuilt via stoking and the addition of coal as a result of a call for shake by the anthrastat at an ash temp lower than 120. In that process, semi-burnt coal will be moved to the ash pan. Under high load conditions, the fire will be often times be stoked and combusted more thoroughly without a call for shake resulting in a more efficient use of coal, burning it more completely because the thicker/hotter fire will stop calls for shake and thus stops the addition of new coal that is not needed.