How to Fix / Troubleshooting

Safety: Turn off power and gas. Allow the unit to cool before touching piping.

Bleed air: Open air vents or bleed valves on the heater and system to remove trapped air.
Check pump and valves: Ensure the circulation pump is running and that all isolation valves are fully open.
Descale heat exchanger: Connect a flushing pump and circulate an approved descaling solution through the heat exchanger until noise is reduced.
Adjust pump speed: If the pump has adjustable speeds, set it according to Buderus recommendations to ensure adequate flow.
Test operation: Restore power and gas, then run the heater and listen for reduction in noise.

Water heater makes loud banging or knocking noises during operation.

Possible Causes