I've got a biomass 25, I've messed around with secondary and primary openings, fan settings and pump settings. I've got dry wood, even used some old hardwood flooring. I get a flame in the lower, mostly yellow-orange sometimes white but I always have white smoke coming out the chimney. This is frustrating considering I just visaited a friend with a tarm and saw how clean these gassifiers can burn. I emailed the fellow who put the fan on his biomass 40 front door. Hope I don't have to do that but I also hope somebody has some suggestions as to what I can try. Told my neighbors that this would be smokeless and now I'm looking a bit foolish.