Fenwal 35-703914-009 Control Board

The Fenwal 35-703914-009 is a 24VAC Micro-Purge Multi-Trial Integrated Ignition Control designed for direct spark ignition (DSI) systems in commercial and residential HVACR applications. This Fenwal ignition module features a 15-second pre-purge period followed by a 7-second trial for ignition (TFI). If the flame is not sensed via the flame rectification circuit, the control board is programmed for three ignition attempts before entering a 1-hour automatic reset or lockout state. Designed to monitor gas valves and inductive loads, this DSI control board utilizes a microprocessor to ensure precise timing and diagnostic LED feedback for troubleshooting. It functions as a direct replacement for various 35-70 series controls, providing reliable gas burner control and sequence management. This Fenwal 35-703914-009 replacement is engineered for high-demand environments, maintaining stable operation despite fluctuations in line voltage or ambient temperature.

• Multi-Trial Sequence: Provides three attempts for ignition to ensure reliable startup in cold-start conditions.
• Flame Sense Logic: Utilizes flame rectification technology for fast response times and precise gas valve shutoff.
• Diagnostic LED: Red LED provides blink codes for rapid system troubleshooting, identifying internal failures or flame loss.
• Remote Flame Sensing: Supports both local and remote flame sensing configurations for versatile installation.
• Encapsulated Design: Protects internal components from moisture and vibration commonly found in rooftop units and boilers.

What does the 1-hour reset feature do?
If the control fails to sense a flame after three trials, it enters a lockout. The 1-hour reset allows the system to automatically attempt the sequence again without manual intervention, reducing unnecessary service calls for nuisance trips.

Can this board replace other 35-70 series models?
Yes, but you must verify the specific purge timing and TFI duration. This model is rated for a 15-second purge and 7-second TFI; using a board with different timings can lead to delayed ignition or premature lockouts.

Why is the diagnostic LED flashing?
A flashing LED typically indicates a specific fault code, such as a "No Flame" signal, "Internal Circuitry Failure," or "Hardware Conflict." Always check the blink pattern against the Fenwal field service manual.

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.