Water heater is excessively noisy during operation (whining, grinding, or rattling)

How to Fix / Troubleshooting

Safety first: Do not insert objects into the flue or fan. Turn off power before touching the appliance.

User checks:

Try to identify whether the noise occurs only when hot water is drawn or also when heating is on.
Bleed radiators (if present) to remove air that can cause pump noise.

Engineer steps:

Listen locally to distinguish between fan noise and pump noise.
Replace the fan assembly if bearings are noisy or there is excessive vibration.
Replace the circulation pump if grinding or rumbling is present.
Check and tighten mounting screws and brackets.

Ignoring mechanical noise can lead to sudden failure; schedule a service visit.