Fraser-Johnston Delayed Ignition

Furnace makes loud banging or booming noise at startup.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Dirty burner ports, Misaligned burners, Low gas pressure, Slow‑opening gas valve

Safety first: Turn off gas and power. Delayed ignition can damage the heat exchanger and is a safety concern.

Inspect burners: Remove the burner assembly if accessible. Clean rust and debris from burner ports with a soft brush and compressed air. Do not enlarge the ports.
Check burner alignment: Ensure burners are seated properly and aligned with the orifices and crossover channels.
Professional gas check: A technician should verify gas pressure and gas valve operation. Do not attempt to adjust gas pressure yourself.

Professional Required 5/5

Burner Assembly

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