The flame should be bright and active, more white than orange, low and compact not tall and wispy. The pellets may roll around a bit lazy but should not “popcorn” out of the burnpot. If your flame is lazy make sure the holes in the burnpot are open and all access doors are sealed. If you have an air inlet control (damper) try pulling it out a bit. Have your pelletstove and flue annually professionally cleaned to ensure maximum efficiency.