A burner alarm (indicated by a red fault light) is typically triggered when the safety lockout mechanism activates due to insufficient fuel supply, ignition failure, or flame sensor anomalies. To quickly troubleshoot and resolve the issue, check for the following common causes:

Fuel Supply Issues: Check if the gas valve is fully open and if the gas pressure is too low or too high; alternatively, check if the fuel supply is exhausted or if the fuel lines are blocked.

Ignition Failure: Repeated ignition failures will trigger an alarm. Clean any carbon deposits from the ignition electrodes and verify that the electrode gap is correct (the standard gap is usually 3–5 mm).

Flame Detector Malfunction: If the surface of the flame detector (photoresistor or UV probe) is obscured by dirt, or if ambient light leaks into the area, the controller may fail to detect the flame and trigger an alarm. Wipe the probe with a soft cloth.

Air Pressure/Flue Anomalies: A faulty air pressure switch or a blocked flue can impede air intake and exhaust, preventing the burner from starting properly.

Emergency Reset Procedure: Allow the unit to cool down completely (usually 3–5 minutes), locate the "Reset" button on the burner controller, press and hold it for 1–3 seconds before releasing, and observe whether the unit restarts.