Dettson furnace makes loud banging or booming noises at startup.

Safety first: Booming ignition can damage the furnace and indicates a combustion issue. Turn off gas and power and contact a qualified technician if the noise is severe.

• 1. Inspect burners (power and gas off): Remove the burner access panel and visually check burners for rust, debris, or misalignment.
• 2. Clean burners: If you are comfortable, remove burners one at a time, brush off debris, and blow out ports with compressed air. Do not enlarge burner openings.
• 3. Check ignitor position: Ensure the ignitor is properly aligned with the burner it lights and is not recessed too far from the gas stream.
• 4. Professional gas adjustment: Gas pressure and combustion should be checked and adjusted by a licensed technician using proper instruments.