Robertshaw 780-502 DSI Module

The Robertshaw 780-502 is a Universal Direct Spark Ignition (DSI) control module designed for single-rod or dual-rod sensing applications in natural and LP gas systems. This gas ignition control operates on 24V AC and provides a 4-second Trial For Ignition (TFI) with a single-try lockout sequence. As a versatile non-prepurge ignition module, it replaces hundreds of legacy Robertshaw and competitive models, including the DS845 and SP715 series. The microprocessor-based circuitry ensures precise timing and reliable flame rectification, critical for preventing nuisance outages in commercial and residential furnaces. This unit features a built-in diagnostic LED for rapid troubleshooting of field faults. When performing a Robertshaw 780-502 installation, ensure properly grounded mounting to the chassis to maintain signal integrity for the 0.7 microamp minimum flame current required for operation.

• Universal Compatibility: Replaces specific Robertshaw, Honeywell, and Penn-Johnson DSI modules with a compact footprint.
• Field Reliability: High-voltage spark output ensures consistent electrode arcing even in high-moisture or low-temperature environments.
• Streamlined Diagnostics: Integrated flash codes allow for immediate identification of system lockouts or hardware failures.
• Flexible Sensing: Supports both local (single rod) and remote (dual rod) flame sensing configurations.

What is the difference between this and a prepurge model?
The 780-502 is a no prepurge module, meaning the spark and gas valve are energized immediately upon a call for heat without a blower delay.

How do I troubleshoot a lockout on this unit?
Verify 24V at the 'TH' terminal. If the unit fails to sense flame after the 4-second TFI, check the flame sensor for carbon buildup or inspect the high-voltage lead for cracks in the insulation.

Can this be used on rooftop units?
Yes, this module is rated for ambient temperatures ranging from -40°F to 175°F, making it suitable for outdoor HVAC cabinets.

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.