Fenwal 35-605611-103 Control

The Fenwal 35-605611-103 is a direct spark ignition (DSI) control module designed for precise gas burner sequencing in commercial and residential heating applications. Operating on a 24VAC 50/60Hz power supply, this microprocessor-based controller manages the gas valve, monitors flame sensing, and executes safety lockdowns. It features a 15-second pre-purge (PP) cycle to clear residual gases and a 7-second trial for ignition (TFI) period. The unit is engineered with high-voltage spark generator circuitry and a single-rod flame sensing configuration. To ensure system reliability, the control includes multi-try ignition logic and flame rectification monitoring. This Fenwal ignition module is a common replacement in forced-air furnaces, commercial water heaters, and boilers, providing robust HVAC flame safety over a wide temperature range. Ensure correct indexing of the edge connector and verify proper grounding to prevent nuisance flame lockouts during commissioning.

Key Benefits

• Advanced Microprocessor Logic: Delivers precise timing for 15-second pre-purge and 7-second TFI, ensuring consistent burner startup.
• Rugged Electrical Sealing: Built to withstand vibration and moisture common in heavy-duty HVAC cabinet environments.
• System Diagnostics: Facilitates rapid troubleshooting of HVAC ignition failure by monitoring the flame signal strength.
• Seamless Integration: Compact footprint allows for easy mounting in existing gas furnace control boards or boiler panels.

Common Questions

How do I troubleshoot a 35-60 series control that won't spark?
Verify the 24VAC input at the L1 and L2 terminals. If power is present, check the high voltage lead for cracks and ensure the spark gap is set to manufacturer specifications, typically 1/8 inch. Insufficient grounding is a frequent cause of DSI ignition failure.

Can this control replace 120V ignition systems?
No, the Fenwal 35-605611-103 is strictly a 24V furnace control. Attempting to apply 120V to this module will Result in immediate component failure. Always verify the secondary voltage of the system transformer before installation.

What is the purpose of the 15-second pre-purge?
The pre-purge cycle is a safety requirement that runs any existing blowers to clear the combustion chamber of unburnt fuel before the spark electrode energizes, preventing delayed ignition or "hard starts."

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.