De Dietrich 83368794 ionisation sensor

This ionisation sensor, listed under De Dietrich part numbers 83368794 and 336.946.064, is an electrode used for flame proving in gas-fired burners. Parts of this type sit in the flame zone and complete a small rectified current through the flame, which the burner control reads as a valid flame signal. Without that signal the control will lock out and prevent fuel flow. The electrode is a consumable component: its tip and ceramic insulator degrade under heat and exposure to combustion by‑products. When selecting a replacement ionisation sensor, the key parameters are the electrode length and bend, the diameter of the insulator, the gap between the electrode tip and the burner head, the mounting flange pattern, and the burner series for which the electrode was originally shaped. Typical failure modes include a cracked ceramic body, an eroded or bent tip, a drifting gap that prevents reliable flame signal, and sooting that insulates the electrode. Burners with a pilot burner use the pilot flame both to light the main burner and to provide the ionisation signal; the electrode is then positioned in the pilot flame path. On burners without a pilot, the electrode senses the main flame directly. When replacing an ionisation sensor of this type, always check the condition of the gasket or sealing surface on the mounting flange. Over‑tightening can crack the ceramic, while a loose fit may cause internal arcing. The electrode cable and its connector to the burner control should be inspected for corrosion or breaks. It is advisable to compare the overall length and the angle of the bent tip against the old part, as the sensing gap is critical for dependable flame proving.