Water heater makes loud clicking, buzzing, or humming noises during operation.

Safety: Turn off power before tightening any internal components.

• Identify noise source: Remove the cover and carefully listen (with power on, if safe and qualified) to locate whether the noise comes from relays, the heat exchanger, or vibrating panels.
• Tighten mounting hardware: With power off, tighten screws securing the heater to the wall and any internal brackets or covers that may vibrate.
• Descale heat exchanger: If the noise resembles kettle boiling or popping, perform a descaling procedure to remove limescale from the heat exchanger.
• Inspect relays/contactors: Look for relays that chatter or buzz excessively. If a relay is failing, the power board may need replacement.
• Monitor: Mild clicking from relays is normal, but persistent loud buzzing or popping should be investigated by a technician.