Fenwal 35-725903-997 Remote Sensor

The Fenwal 35-725903-997 Remote Sensor is a critical diagnostic and flame-monitoring component designed for integration with Fenwal series ignition controls, specifically the Mark 10DX-117 and 35-72 series boards. Engineered for high-temperature ionization sensing, this probe monitors flame conductivity to ensure safe and reliable furnace operation. Contractors typically deploy this surface-mount flame sensor in commercial and residential HVACR applications where a remote flame probe is necessary to provide feedback to the DSI (Direct Spark Ignition) module. The sensor features a 1/4-inch male quick-connect terminal for rapid field installation and is rated for extreme thermal environments to prevent premature ceramic cracking or signal loss. By accurately detecting the microamp signal generated during combustion, the Fenwal 35-725903-997 prevents nuisance lockouts and ensures the ignition control board maintains gas valve voltage only when a pilot or main burner flame is verified.

• Universal Compatibility: Optimized for use with Fenwal 35-72 series and Mark 10DX control systems.
• Enhanced Signal Integrity: Designed to deliver consistent microamp feedback even in high-static environments.
• Durable Ceramic Insulation: High-grade alumina ceramic prevents voltage leakage to ground in flame sensing circuits.
• Easy Retrofit: Standard mounting footprint allows for quick replacement of fouled or cracked HVAC flame probes.
• Critical Safety Compliance: Ensures immediate gas shut-off upon loss of flame ionization detection.

What causes a Fenwal flame sensor to fail?
Failure is usually caused by carbon buildup (soot), oxidation of the probe rod, or a cracked ceramic insulator. Before replacing the 35-725903-997, check for microamp signal strength between the sensor and the ignition module.

Can I clean this remote sensor instead of replacing it?
While light oxidation can be removed with steel wool or emery cloth, any signs of ceramic fractures or deep pitting on the rod require a full Fenwal sensor replacement to ensure system reliability.

Does this sensor work with other ignition brands?
While many flame rods operate on the same principle, the 35-725903-997 is specifically calibrated for Fenwal control boards. Always verify mounting dimensions and terminal types when cross-referencing components.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.