NATE HVAC Support Technician Practice Test

Flexible duct needs physical support so it doesn’t sag or pull away from fittings, which would increase resistance, cause leaks, and stress connections. The standard practice is to secure it at regular intervals no more than four feet apart. Placing supports closer to each connection (within about a foot) helps prevent movement at the joints. Tape alone doesn’t provide structural support and will not reliably stop sagging, and eight-foot spans are too long and allow sagging and kinks. So the best practice is supporting the duct every four feet to keep airflow consistent and the system durable.