Boiler makes loud banging or knocking noises when starting or stopping

Safety: Turn off power and allow the boiler to cool before bleeding or inspecting piping.

• Step 1 – Bleed air: Use air vents and radiator bleeders to remove trapped air from the system. Refill to proper pressure.
• Step 2 – Check flow: Ensure all zone valves and isolation valves are open and the circulator pump is operating correctly on the Triangle Tube boiler.
• Step 3 – Inspect piping supports: Look for loose or unsupported pipes that can bang when flow starts or stops. Add or tighten pipe clamps as needed.
• Step 4 – Descaling (professional): Persistent kettling (boiling sounds) often indicates scale in the stainless steel heat exchanger. A technician should chemically flush the boiler using an approved descaling solution.