What type of ducts are prohibited in clothes dryer installations, except for the transition duct?

In the context of clothes dryer installations, the use of flexible ducts is often restricted, except for the transition duct, which is specifically designed for short connections between the dryer and the main duct system. This limitation exists because flexible ducts can easily become crushed or kinked, which can restrict airflow and create a fire hazard by preventing heat and moisture from exiting properly.

Rigid metal ducts, on the other hand, are preferred for dryer venting as they provide a smooth interior surface that minimizes friction and allows for better airflow. Collapsible ducts, while they may be convenient, also do not meet the performance and safety standards required for long-term use in dryer venting applications. Ventilation ducts are generally designed for different purposes, such as HVAC systems, and are not suitable for drying clothes.

Therefore, the prohibition of flexible ducts in general dryer installations underscores the focus on safety and efficiency, emphasizing the importance of using the appropriate type of duct to ensure safe and effective venting.