Protherm Delayed Ignition / Burner Light‑off Problem

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 main burner on Protherm heat exchanger, Incorrect gas pressure, Misaligned ignition electrode, Slow‑opening gas valve

Safety first: Turn off power and gas. Booming ignition can damage the furnace and flue; do not ignore it.

Step 1 – Burner inspection: Remove the burner and inspect for rust, debris, or blocked ports. Clean carefully with a soft brush and vacuum.
Step 2 – Ignition electrode position: Verify that the electrode is correctly positioned relative to the burner as per the Protherm manual.
Step 3 – Technician gas check: A licensed technician must verify gas pressure and valve operation. They may need to adjust or replace the gas valve.

Hard 4/5

Main Burner Assembly

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