What is the maximum allowable length for a flexible duct connector?

What is the maximum allowable length for a flexible duct connector?

• A. 14 feet
• B. 10 feet
• C. 20 feet
• D. 24 feet

Answer: (A)

Flexible duct connectors are used to join the blower to the duct system, but they add more friction and potential leakage than rigid duct. Because of that, codes limit how long these flexible sections can be. The upper limit for residential installations is 14 feet, which helps preserve adequate airflow and static pressure while minimizing leaks. If you need a longer run, the design should rely more on rigid duct segments with only short flexible portions near the connections. Longer options would exceed the allowed length, while shorter ones stay within the limit, making 14 feet the maximum allowable length.

Flexible duct connectors are used to join the blower to the duct system, but they add more friction and potential leakage than rigid duct. Because of that, codes limit how long these flexible sections can be. The upper limit for residential installations is 14 feet, which helps preserve adequate airflow and static pressure while minimizing leaks. If you need a longer run, the design should rely more on rigid duct segments with only short flexible portions near the connections. Longer options would exceed the allowed length, while shorter ones stay within the limit, making 14 feet the maximum allowable length.