Fenwal 35-703920-009 Board

As a technician, you know that intermittent ignition failures are usually traced back to a failing control module. The Fenwal 35-703920-009 Ignition Control Board is a specialized 120V DSI (Direct Spark Ignition) module engineered for precision timing and flame monitoring in residential and commercial atmospheres. This Fenwal 35-70 series control utilizes a microprocessor to provide constant self-diagnostics and safe-start checks, ensuring the gas valve only opens when the flame sense current—which requires a minimum of 1.0 microamp—is confirmed. Designed for versatility, this board is conformal coated to maintain operational integrity in high-moisture environments up to 95% RH, making it a rugged choice for rooftop units, boilers, and unit heaters. When performing a Fenwal ignition control replacement, this OEM component ensures compatibility with Natural, LP, and Manufactured gases, meeting the high-demand specs of HVAC 120V ignition systems.

Key Benefits for the Contractor:

• Extreme Temperature Resilience: Rated for operation from -40°F to +175°F, preventing nuisance lockouts during cold weather startups.
• Advanced Flame Detection: Features a lightning-fast flame failure response time of ? 0.8 seconds to prioritize system safety.
• High-Moisture Protection: The conformal coating prevents circuitry corrosion in demanding mechanical rooms or outdoor cabinets.
• Universal Gas Compatibility: Eliminates the need for multiple stock items, working seamlessly with propane and natural gas configurations.
• Standardized Electrical Specs: Operates on 102–138 VAC with a 1.5A gas valve rating, matching standard DSI control board specifications.

Common Questions:

Is the 35-703920-009 compatible with multisetup mounting?
Yes, this board supports multiple mounting configurations including integral stand-offs, potted, or enclosed in a case with a cover, depending on your specific furnace or boiler cabinet layout.

What is the spark rate for this ignition module?
The spark rate for the Fenwal 35-703920-009 is tied to the line frequency at 50/60 Hz, ensuring a consistent arc for reliable pilot or main burner ignition.

How do I troubleshoot "No Flame" errors with this board?
First, verify your flame sense voltage is at 120 VAC and check that the flame rod is clean. If the sense current holds below 1.0 microamp, the board will initiate a safety lockout.

California Proposition 65 Warning: This product may contain materials known to the state of California to cause cancer and/or reproductive harm.

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.