The new damper actuator/thermostat has been working great!
The house temperature seems to stay very level. I've only noticed the furnace run two times, both times being first thing in the morning, after loading fresh coal, before it had a chance to get "up and going". I do have the T-stat set back for night, but on the "min/max thermometer" the temp doesn't seem to have dropped all that far through the night.
The pea coal seems to burn good and shake down better than the nut - in my stove.
I've been wondering about this type of coal firing - "full draft/minimum draft" cycles, in regard to ash, complete coal burn, efficiency, etc..