Anthratherm Air Setting

I was wondering what the suggested air flow setting is on my Anthratherm VA600. It was set on 4 but I backed it off to 3.5 to get the fire higher in the pot. I was thinking that the fire should be as high in the pot as possible without seeing unburnt coal in the ashes. I was also wondering if anyone knew if what the model numbers designated? In other words do the larger model numbers denote a larger furnace or vice versa? I also was wondering what the BTU rating is for my stoker boiler.

The Beacon boiler book lists your VA 600 as having a coal feed rate of 18 lbs per hour. Using a BTU value of 13000 btus/lb and an efficiency of 80% you get an approximate rating of 180k btus/hr. This is just a ballpark figure, I've never read any official efficiency ratings for the Van Wert units and the BTU content of the coal can vary.

The BTU output rating is roughly 110-120K BTU. These are conservative numbers.
Your fire should have a perimeter of burnt ash, an inch or two wide, the center should be all red coals, the very center may be a bit darker.
The underfeed type stokers like you have rarely have unburnt coal because of feed or air adjustments.. only if the adjustments are way off.. if you have unburnt coal in your ashes, it is probably poor quality coal that has some 'bone' or refuse coal mixed in.. A little bit is not a problem..

Underfeed type stokers will burn just about any quality coal as completely as it can be burnt..

Hope this helps.

Greg L