Heater operates but creates a whistling or high-pitched noise from the gas train.

Safety first: Turn off gas and power before inspecting the gas train. Gas work should be performed by licensed professionals.

• Listen for source: Identify whether the noise comes from the gas valve, manifold, or burners.
• Check gas piping size: Have a gas technician verify that the supply line size and length meet Thermeau requirements.
• Inspect orifices: A technician can remove and inspect burner orifices for debris and clean them without altering size.
• Regulator adjustment: The gas regulator may need fine adjustment or replacement to eliminate oscillation.
• Do not modify orifices: Never drill or enlarge orifices to reduce noise; this is unsafe and voids certification.