Furnace causes noticeable vibration and rattling through the ductwork or pipework.

Safety: Excessive vibration can loosen gas and water connections over time. Inspect visually with power off.

User checks:

• Ensure nothing is leaning against the furnace casing.
• Note when vibration occurs (start-up, running, shutdown) and inform the technician.

Technician checks:

• Tighten all mounting screws and brackets on the furnace and fan.
• Check fan impeller for damage or imbalance.
• Secure and clip pipework and ducting to prevent resonance.