What feature must be included in ductwork for dryer exhaust systems to ensure proper functionality?

In dryer exhaust systems, including a backdraft damper is essential for ensuring proper functionality. This feature serves a crucial purpose by preventing cold air, pests, or debris from entering the ductwork when the dryer is not in operation. When the dryer is running, the backdraft damper opens to allow the hot, moist air to escape outside. Once the dryer is turned off, the damper closes, effectively sealing the duct system. This helps to maintain energy efficiency and hygiene, reducing the likelihood of moisture accumulation and potential mold growth within the ductwork.

Other components like a turn radius can help manage airflow and reduce restrictions, while anti-vibration mounts may help minimize noise and vibration from the dryer. Insulation layers might be employed to prevent condensation in certain climates, but without a backdraft damper, the system would be vulnerable to air infiltration, leading to inefficiencies and increased risk of issues like lint buildup or backflow of exhaust air.