Furnace makes loud banging or booming noises at startup

Safety first: Booming at startup can indicate dangerous combustion conditions. Turn off gas and power and do not continue to operate the furnace until inspected.

Steps:

• Visual burner inspection: With power and gas off, remove the burner assembly and inspect the burner head and ports for rust, debris, or soot. Do not enlarge or modify ports.
• Check ignition electrode position: Verify that the Danfoss ignition electrodes are correctly gapped and positioned per the burner manual so that the spark occurs where gas first emerges.
• Do not adjust gas pressure yourself: Gas pressure and air settings require manometers and combustion analyzers. Contact a qualified technician to clean and adjust the burner and verify gas valve operation.