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RV Motors & Parts - Parts & Accessories - Electrodes

Electrodes serve an important function in propane based furnace systems, specifically ones used in RV's and campers.  They serve a dual purpose as both the spark igniter and the flame sensor in most modern electronic ignition setups, using a single rod or assembly (often a 1- or 2-prong design) positioned near the burner ports. The control board sends high-voltage pulses through the electrode to create a visible spark across a small gap (typically 1/8" to 1/4") to the grounded burner or a separate ground probe, igniting the propane-air mixture when the thermostat calls for heat and the gas valve opens—ensuring reliable startup in the compact, mobile environment.

Once the flame is established, the electrode acts as a flame sensor via flame rectification: the flame's ionization creates a tiny DC microamp current (rectified by the flame) that flows from the electrode (now acting as a probe) through the flame to the grounded burner and back to the control board, proving flame presence and allowing the board to keep the gas valve open for continuous heating; if the signal is lost (due to dirty/coroded electrode, poor gap, weak flame, or wiring issues), the board shuts off the gas to prevent unsafe gas release, often leading to lockout after retry attempts and requiring cleaning, gapping, or replacement to restore reliable operation.