Heater makes loud banging or knocking noises during operation.

Safety first: Turn off power and allow the heater to cool. Do not continue operating a heater that is banging; damage can occur.

• Check flow indicators: Ensure the pump is fully primed and that the filter pressure is within normal range. Very low or very high pressure can indicate flow problems.
• Bleed air: Open any air relief valves on the filter or high points in the system to remove trapped air.
• Clean filter and baskets: Backwash or clean the filter and clear all skimmer and pump baskets.
• Inspect for scale: If banging persists, internal scale may be causing localized boiling in the Thermeau heat exchanger. Schedule a professional descaling service.
• Verify pump sizing: Ensure the pump and plumbing are correctly sized for the heater’s required flow rate.