Noisy vibration or humming from the water heater when running.

Safety: Isolate power before touching the appliance or pipework.

• Check casing screws: Ensure all front and side panel screws are tight to reduce resonance.
• Inspect mounting: Confirm the heater is securely fixed to the wall and not rocking.
• Support pipework: Add or tighten pipe clips near the heater to prevent pipes from vibrating against walls or each other.
• Persistent noise: If noise seems to come from the pump or fan, have a technician inspect and replace worn components.