Fenwal 35-725201-505 Control

The Fenwal 35-725201-505 is a robust 120V Direct Spark Ignition (DSI) control designed for heavy-duty gas-fired equipment. This microprocessor-based ignition module is engineered for precise timing and sequence management, featuring a 5-second prepurge to clear the combustion chamber and a 10-second trial for ignition (TFI). Built to handle the rigors of industrial heating and commercial water heater applications, it operates as a single try ignition control with local flame sensing. The unit utilizes a multi-pin connector for secure wiring and a spark transformer output capable of delivering reliable electrode discharge in demanding environments. This control is frequently used as a direct replacement in systems requiring intermittent pilot or direct spark logic where 120VAC line voltage and 120VAC thermostat signals are standard. Its diagnostic LED assists technicians in rapid troubleshooting of lockout conditions or flame signal issues, ensuring minimal downtime for critical HVACR infrastructure.

• Precise Prepurge Timing: The fixed 5-second prepurge ensures gas-fired appliances meet safety standards by venting residual gases before the spark ignition sequence begins.
• Optimized Trial for Ignition: A 10-second TFI window provides sufficient time for flame stabilization on high-input burners, reducing nuisance lockouts.
• Simplified 120V Integration: Designed for standard 120VAC power and load requirements, making it a drop-in replacement ignition module for a wide range of commercial boilers and furnaces.
• Robust Local Sensing: Utilizes the spark electrode for flame rectification, simplifying the wiring by eliminating the need for a separate remote flame probe.
• Microprocessor Reliability: Delivers consistent timing accuracy across varying temperature and voltage conditions, unlike older analog controls.

Is the Fenwal 35-725201-505 compatible with 24V thermostats?
No, this specific model is designed for 120V operation. Both the input power and the thermostat signal must be 120VAC. Using 24V control circuits on this module will result in failure to energize.

What does 'Single Try' mean for this ignition sequence?
In a single try ignition configuration, if the flame is not sensed during the 10-second TFI, the module will enter a safety lockout. To reset the control, the thermostat must be cycled or power must be removed and reapplied.

Can I use this control in a remote flame sensing setup?
This model is configured for local flame sensing, meaning it looks for the microamp flame signal back through the high-voltage spark cable. Ensure your burner assembly is grounded correctly to complete the rectification circuit.

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.