I closed the damper a little and the flame seems higher. Is there such thing as too high. I am getting some brown soot on my glass and wipe most of it off daily, scrub the window weekly. My friend burns the same pellets (a different stove) and only has to clean his glass weekly. If the flame is not brown on the tips should I continue to close the damper more. (I should add it is an insert in a 35 ft chimney.)