I'm planning on burning on setting #3 (out of 5). I am getting really good heat, but my flame is barely visible through the bay window of the stove. It is mostly down in the burn pot and coming up 6-8 inches. I want to burn efficiently, so would setting the flame higher by adding more air or by increasing the pellet feed rate really lower the efficiency of the stove? Also a lot of the pics of stoves I see are burning with a 18" to 22" flame. How close should the flame be to the heat exchange tubes, without burning too hot or too inefficiently?