What is the requirement for fire dampers and similar devices in clothes dryer exhaust ducts?

The requirement for fire dampers and similar devices in clothes dryer exhaust ducts is that they are prohibited. The primary reason for this prohibition is that clothes dryer exhaust systems must operate effectively without obstruction to allow for the safe expulsion of hot air, moisture, and lint. Fire dampers can interfere with the normal airflow, leading to potential hazards such as lint buildup and reduced dryer efficiency, increased risk of overheating, and even fire hazards.

Additionally, any obstructions imposed by fire dampers can prevent proper venting, contributing to appliance inefficiency and creating an environment where combustion gases might accumulate, which is particularly dangerous in a residential setting. The designed intent of dryer exhaust systems is to provide a clear and unobstructed path for exhaust, ensuring both safety and functionality. Thus, fire dampers are not compatible with the requirements set forth for clothes dryer exhaust ducts.