Heater makes loud banging, popping, or rumbling noises during operation

Safety First: Turn off power and gas. Allow the heater to cool completely before touching plumbing.

• Check and improve flow: Clean the filter, ensure pump is at proper speed, and verify all valves to and from the heater are fully open.
• Bleed air: If the system has air bleeders, open them to release trapped air. Ensure the pump is fully primed.
• Inspect bypass settings: Adjust internal/external bypass per Rheem instructions to ensure sufficient flow through the exchanger.
• Schedule descaling: Persistent kettling usually indicates scale. Have a professional chemically descale or, if necessary, replace the heat exchanger.