Fenwal 35-655700-003 Control

The Fenwal 35-655700-003 is a microprocessor-based 24V Hot Surface Ignition (HSI) control engineered for precision in gas-fired appliances. Built for reliability in demanding HVACR environments, this ignition module manages the call for heat by supervising the combustion blower, verifying airflow through the pressure switch, and controlling the igniter heat-up sequence. This specific 35-65 series control is configured for a single try for ignition with a 7-second trial for ignition (TFI) period. It features 0-second pre-purge and 0-second inter-purge timings, making it an ideal direct-replacement ignition board for systems requiring immediate energization of the HSI element upon a call for heat. The onboard LED diagnostics simplify troubleshooting by providing clear flash codes for system faults like internal failure, airflow errors, or flame signal loss, ensuring minimal downtime for contractors in the field.

• Precise Microprocessor Control: Delivers repeatable 7-second TFI timing and consistent safety checks for burner operation.
• Robust Diagnostic Interface: Integrated diagnostic LED provides instant feedback for rapid fault isolation and flame sensing verification.
• Multi-Appliance Compatibility: Designed for use in commercial boilers, furnaces, and water heaters requiring 24 VAC HSI control.
• Superior Flame Monitoring: Utilizes Detect-A-Flame technology for sensitive flame rectification (0.7 microamps minimum) to prevent late-ignition scenarios.

• How do I test the flame signal on this Fenwal control? Use a DC microammeter connected to the FC+ and FC- terminals; a healthy signal should read 1.0 µA or higher.
• What does a steady LED light indicate during a call for heat? A steady-on LED typically indicates an internal control board failure requiring a system reset or replacement.
• Can I use this to replace a multi-try ignition module? No, this model is a single-trial ignition unit; always match the retry logic and TFI timing to the original equipment manufacturer's specifications.

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.