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

Safety first: Turn off power and allow the boiler to cool before touching piping.

• Step 1 – Bleed air: Air pockets can cause banging. Bleed radiators and high points in the system. Check that automatic air vents are functioning and not leaking.
• Step 2 – Inspect piping supports: Ensure that supply and return pipes are properly supported and not rubbing against framing. Add or adjust pipe hangers as needed.
• Step 3 – Check temperature rise: Verify that the boiler is not set to an excessively high temperature. Lower the setpoint slightly if appropriate for your system.
• Step 4 – Descale heat exchanger (pro): Kettling (tea-kettle-like noises) often indicates scale inside the heat exchanger. A professional should perform a chemical descaling using Bradford White-approved procedures.
• Step 5 – Verify flow rate: Ensure the circulator pump is correctly sized and operating. Low flow can cause localized boiling and noise.

Warning: Do not ignore persistent kettling; it can damage the heat exchanger over time.