lsayre wrote:I'm hoping that colder weather will bring increased efficiency and less unburned coal in my S130's ash pan. I still have my differential at 10 degrees, but I just dropped my ash grate temperature control setting down to 120 degrees.
I have noticed that the ashes collected in the pan at night have less unburned coal in them then the ashes that collect during the heat of the day (which are loaded with coal).
Some coal just won't burn, but stokers in general have unburned coal in the ash. It's just the nature of the beast. The Axeman/AHS boilers by their design are prone to have more at idle. The reason is that they were built to extract the most usable heat from a pound
of coal than anything else. They did this by a sort of Rube Goldberg design. Its fan is on the backside, the fire sits in inches of ash and can't get air through it at idle. Not sounding like a great coal burner is it? It's made to run flat out and when it stops, the observation port opens and breaks the draft through the fire and tries to kill it. The fire is completely surrounded by hot water, reducing its heat loss and the draft going above the fire doesn't pull heat from it and stops oxygen from feeding it so it essentially goes out at idle. Of course it can't because there is a 20+# mass of coal that is at a scary temperature, any oxygen gets to it and it is going like gangbusters again.
All this nonsense aside, unless it is excessive, unburned coal in your ash is not a problem. Because
of their screwball design, they are, even with a lot of unburned coal coal in the ash is still more efficient than anything else on the planet
. So don't worry about the unburned coal, just heave it with the ash and smile because you have what you got!