The fan system uses a variable flow rate to fine-tune the amount of oxygen given to the fire. All fans are equipped with an adjustable damper and an aluminum nozzle. The slide damper can be completely closed to kill the fire or can be adjusted to a small opening for cold smoking. This feature allows fine adjustments to be made due to natural drafts that effect cooking temperature during the fan’s off cycle. Open the damper fully for quick startup. Close halfway to two-thirds of the way for smaller cookers or low and slow cooking. Close nearly all the way for cold smoking.