Pellet stoves are zone heating appliances. They are similar to wood stoves, but instead of burning wood logs, pellet stoves burn pellets made of wood or corn. Pellets are fed into the burn grate of the stove where combustion will take place. If the air flow in the burn grate is too high, the burning pellets will lift up off the burn grate and become airborne. This is called popcorning because the pellets resemble kernels of popcorn jumping into the air as they pop. Popcorning is not a desirable condition in your pellet stove and needs to be rectified.
Observe the fire in your pellet stove. The flame should be yellow and brisk enough to carry ash out of the burn grate, but not so brisk that the pellets popcorn.
Open the pellet stove's damper if the fire is orange and red with soot at the top of the flame. Open the damper 1/8 inch at a time until the fire is yellow and brisk.
Close the damper if the fire is yellowish white and burning briskly enough to popcorn the pellets. Close the damper 1/8 inch at a time until the fire is the right color of yellow and is burning briskly so the ash flies out of the burn grate.