I finally got around to plaing with direct control of the blower on my Eko 25. I'd like to write a smarter control algorithm than what's in the Eko controller. I haven't installed my lambda sensor yet, but I do measure combustion and flue temperatures. Combustion sensor is a bit away from the actual secondary combustion to preserve sensor life. Seems like the first question is "What's the relationship between fan speed and combustion temp at different points in the combustion cycle?" Having lots of opinions but no data, I did a fire today with lots of refuel events, and varied the fan speed at various points to see what happened. Here's a chart - fan speed varied from 30% to 100%. Not sure I can draw many conclusions from it, except faster is definitely not always hotter. Any thoughts or insights? Combustion temp and flue temp are divided by 10 to fit on chart.