High-pitched whistling or howling noise from the water heater during operation

Safety: Turn off power and gas before opening combustion components. Gas adjustments must be done by a professional.

• Check water valves: Ensure all service valves on the cold inlet and hot outlet are fully open to reduce velocity noise.
• Inspect burner: Clean burner ports and ensure even flame distribution. Do not modify port size.
• Check flue supports: Make sure the flue is properly supported and not vibrating against structures.
• Professional gas check: Have a technician verify gas pressures and adjust if necessary to eliminate combustion resonance.