With a fan-controlled firebox, you need to be able to adjust the amount of air being blown into the firebox. In addition, natural draft may affect cooking temperature when the fan is off. While arriving at final settings requires testing and experimentation, as a general rule it is good to start with the slide damper fully open on offset and large cabinet smokers, halfway open on medium-size vertical or cabinet smokers, and one-third to half open on kettles, bullet, and ceramic smokers. This should support cooking from 225° F to 275°F. Note that it is more efficient for the fan to provide enough air to raise the cooking temperature a few degrees high than to labor consistently a few degrees low.
The top damper functions differently with a fan-controlled system than with a natural-draft system. Where the fan damper controls the amount of air flowing into the smoker, the top damper influences the amount of air flowing out. We recommend keeping the top damper as little as possible in order to retain heat and smoke in the cooking chamber, consistent with reaching the desired cooking temperature.
Close the damper completely to extinguish the fire after cooking (you can also remove the fan and insert a silicone “kill plug” into the adapter).