How to Fix / Troubleshooting

Safety first: Switch off power and allow the unit to cool before touching the cylinder or pipework.

Step 1 – Check temperature setting:
- Ensure the setpoint is not excessively high; reduce to around 55–60 °C if higher.
Step 2 – Bleed air and verify circulation:
- Bleed air from the primary circuit and ensure the circulation pump is running correctly.
Step 3 – Descale:
- Arrange for professional descaling of the immersion heater and, if necessary, the coil. This often resolves kettling noises.
Step 4 – Sensor position:
- Confirm that the tank sensor is fully inserted into its pocket to prevent overshoot.

Persistent loud banging can stress the system; have a technician inspect if noises continue after descaling.

Water heater makes loud banging or knocking noises when heating.

Possible Causes