De Dietrich S101566 ionisation electrode

This is an ionisation electrode for De Dietrich burners and boilers. It is listed under the catalogue numbers S101566 and 336.946.029. Parts of this type are used to prove the presence of a flame by passing a small rectified current through the flame envelope. The electrode sits directly in the flame zone, typically near the burner head or pilot burner. Unlike an ignition electrode, which delivers a spark, the ionisation electrode does not generate a spark; it only senses the flame. The signal it produces is read by the burner control (flame safeguard) to confirm that fuel is burning, and if the signal is lost the control will lock out for safety. Ionisation electrodes are consumable items. Their service life is limited by exposure to heat and combustion by-products. Selection is based on physical configuration: the length and bend of the rod, the diameter and type of the ceramic insulator, the mounting flange or bracket design, and the gap between the electrode tip and the burner ground. These parameters are specific to the burner model and the combustion head geometry. Common failure modes include erosion of the tip, cracking of the ceramic insulator due to thermal shock, carbon sooting that bridges the gap, and a drifting gap that lengthens ignition time. When replacing an electrode of this type, always check the tip condition, the insulator for hairline cracks, and the mounting seal. The gap must be set to the burner manufacturer’s specification; a gauge may be required. In systems with a pilot burner, the ionisation electrode often proves the pilot flame first, then the main flame is allowed to light.