Fenwal 35-655605-003 Control

The Fenwal 35-655605-003 is a microprocessor-based 24V HSI ignition control designed for precise sequence management in gas-fired heating equipment. Engineered for high-reliability applications, this hot surface ignition module utilizes intensive diagnostic logic to monitor the thermostat, pressure switch, and main burner flame. It features a 3-try ignition strategy with a 7-second trial for ignition (TFI), ensuring robust performance in demanding environments. This specific configuration operates with 0-second pre-purge and 0-second inter-purge timings (0IP), providing immediate ignition sequencing upon a call for heat.

As a veteran-grade HVAC replacement part, the 35-655605-003 control board is a direct cross-reference for the obsolete Fenwal 35-655516-003. Its compact, non-position-sensitive design allows for flexible mounting in furnaces, boilers, and commercial water heaters. The on-board LED diagnostics simplify troubleshooting by providing clear fault codes for airflow failures, flame sensing issues, and internal hardware checks. Technical professionals favor this module for its consistent combustion monitoring and 0.8-second flame failure response time, maintaining system safety and operational efficiency.

Key Benefits

• Direct Replacement Compatibility: Serves as a technical upgrade for the discontinued 35-655516-003 and other 35-65 series modules.
• Advanced Diagnostics: Features a multi-code LED indicator to rapidly identify ignition lockouts and pressure switch faults.
• Precise Timing: Microprocessor control ensures repeatable 7-second TFI and 3-trial ignition sequences for reliable burner startup.
• Safe Operation: Continuous flame monitoring with a high-speed response to flame loss helps prevent hazardous gas accumulation.
• Durable Construction: Built to withstand ambient temperatures up to 175°F (80°C) and vibration common in industrial HVAC cabinets.

Common Questions

A 3-flash code typically indicates an ignition lockout. This occurs when the module fails to sense a flame after the three programmed trials. Technicians should verify the hot surface ignitor integrity, check for 24V at the gas valve, and ensure the flame sensor is generating at least 1.0 microamp of current.

The 35-655605-003 is a 0IP (zero inter-purge) and 0PP (zero pre-purge) model. If your specific appliance requires a blower lead-time or combustion chamber clearing prior to ignition, you must select the Fenwal variant with the appropriate timing suffix.

For this 24V HSI control, the microprocessor requires a minimum flame sense signal of 1.0 microamp DC. Readings below this threshold will result in the system cycling or entering lockout to ensure safe operation.

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.