Fenwal 35-615521-203 Module

The Fenwal 35-615521-203 is a 24v DSI ignition module engineered for high-performance gas-fired appliances including furnaces, boilers, and water heaters. As a microprocessor-based control, it provides precise sequencing and safety monitoring for direct spark ignition systems. This specific model features a 30-second pre-purge to clear the combustion chamber and a 7-second trial for ignition (TFI) to ensure reliable burner startup. Built with an integrated inducer blower relay and 30-second post-purge functionality, it manages the full combustion cycle while protecting against transient power surges. The Fenwal 35-60/61 series is known for its rugged construction and on-board diagnostics, utilizing a diagnostic LED to simplify Field troubleshooting. Technicians can utilize the flame sense test pins to verify a minimum 0.7 microamp signal, ensuring the DETECT-A-FLAME technology is properly supervising the burner. This module supports local or remote flame sensing and is designed for easy mounting in any orientation within standard HVAC cabinets.

• Efficient Combustion: Integrated 30-second pre-purge and post-purge cycles ensure the heat exchanger is clear and safe for each cycle.
• Streamlined Troubleshooting: The diagnostic LED provides instant error codes for common issues like airflow faults or ignition lockouts.
• Consistent Performance: Microprocessor control eliminates the timing drift found in older analog modules, providing a stable 7-second TFI.
• Flexible Integration: Works with natural gas, LP, or manufactured gas systems and supports both local (through the spark electrode) and remote flame sensing.
• Industrial Durability: Conformal-coated circuitry protects the 24V ignition control from moisture and environmental contaminants.

• How do I reset the module after an ignition lockout? For the 35-615521-203, you can reset the system by cycling the thermostat call for heat or removing the 24V power source for at least 5 seconds.
• What does a steady LED light indicate during operation? A steady LED typically indicates an internal control failure or a "dead" module; verify 24 VAC at the TH/W terminal before replacing the unit.
• Can this module replace other 35-60 or 35-61 series controls? Check the specific timing (Pre-purge/TFI) and sensing type (Local/Remote) of your existing module to ensure Fenwal cross-reference compatibility.

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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.