Stoker Likes the Red Ash

when my stoker burns the red ash it thoroughly burns all the coal, but when I use white ask coal there is a good bit of unburnt coal in the ash pan and seams to happen when the col-trol ask it to go from a day time idle to a evening fireup ,Its like my idle rate is to low and the coal fire bed is small and slow to catchup ,, just to say in a hand full of ash you may find 5 or more pieces of coal ,,, any thoughts?

I too like red ash coal with my Keystoker 90. Red ash can contain more BTU's and burn hotter. The old hopper fed Buderus was hell at times with red ash, been there done that. It's a KLINKER Christmas story