Boiler makes loud banging or knocking noises when starting or during operation

Safety: Noisy operation can indicate overheating. Monitor system pressure and temperature; shut down if they exceed limits.

• Bleed air: Vent radiators and high points to remove trapped air that can cause banging.
• Check flow: Ensure all valves are open and the circulation pump is operating. Verify filters and strainers are clean.
• Secure piping: Add or tighten pipe clamps and supports to reduce movement when pipes expand.
• Descale heat exchanger: Persistent kettling (tea‑kettle sound) often indicates scale. A technician should chemically flush the NTI heat exchanger using an approved descaling solution.