Heater makes loud banging or knocking noises during operation.

Safety first: Turn off power and gas. Allow the heater to cool before touching any metal parts.

• Increase flow: Verify pump speed and valve positions to ensure strong flow through the Kripsol heater. Clean the filter if dirty.
• Bleed air: If the heater has an air bleed valve on the manifold, open it slightly to release trapped air until water flows steadily.
• Lower setpoint: Reduce the temperature setting to a more moderate level to reduce boiling risk.
• Descale exchanger: Persistent kettling usually indicates scale. Arrange for a professional to chemically descale the Kripsol heat exchanger following manufacturer guidelines.