Boiler Electrodes: Ignition and Flame Detection

Electrodes are the main component for ignition and flame detection in modern boilers. They are divided into detection electrodes and ignition electrodes, located near the burner, and report to the ignition and modulation board about the burner’s flame status.

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Detection Electrode

The boiler’s detection electrode is an electronic component used in gas boilers to detect the presence of a flame inside the combustion chamber, near the burner. The electrode works by sending a current to the boiler’s board, thereby communicating that a flame is lit.

Flame Lockout Error

During a flame lockout error, the detection electrode cannot detect the microampere produced by the flame at the board. The electronic board gives a variable time to ignition, up to 7 seconds. At the end of this time, the boiler locks and goes into a blocking error that requires a reset or rearming.

Ignition Electrode

The ignition electrode is an electronic component used to ignite the gas in the combustion chamber of the boiler. The electrode works by sending a high-voltage electric discharge to the spark plug, which in turn creates a spark to ignite the gas. The same electrical arc initiates the combustion of the gas and ignites the burner.

Double Ignition

In case of problems during the ignition phase, with a clean and maintained burner, it’s possible that the gas in the burner ignites too late, causing strong explosions during ignition.

Problems Arising from the Ignition Electrode

Strong Explosions during Ignition

Strong explosions during ignition can occur if the current is discharged elsewhere through the ignition spark plug’s cable.

External Parasitic Discharges to the Combustion Chamber

In very old boilers, the ignition electrode may deteriorate in the cable, such that the electrical arc occurs far from the burner’s ramp. In such a case, it’s necessary to replace the ignition electrode.