Lochinvar & A.O. Smith 100077872 Control

The 100077872 (GSW 52720) is a genuine OEM hot surface ignition (HSI) control specifically engineered for select Lochinvar and A.O. Smith gas-fired water heaters. As a veteran-grade electronic ignition module, this component manages the critical timing sequences for the ignitor warm-up, gas valve actuation, and flame rectification sensing. It operates on a 24 VAC control circuit, integrating high-performance microprocessor logic to ensure precise flame signal monitoring and reliable burner startup. This replacement ignition board replaces legacy part numbers and factory-installed units in EnergyRite and Copper-Fin systems, providing an exact-fit solution that eliminates nuisance lockouts. For contractors, the 100077872 offers a rugged interface for intermittent pilot or direct HSI applications where consistent 120V power to the ignitor is required. By maintaining the correct timing and diagnostic parameters, this control restores system efficiency and prevents hazardous unburned gas buildup during failed ignition trials.

• OEM Compatibility: Guaranteed fit for A.O. Smith, Lochinvar, and John Wood (GSW) residential and commercial gas units.
• Stable Flame Sensing: Robust rectification circuitry prevents false flame-out codes and short-cycling.
• Technical Reliability: Engineered for high-temperature environments and continuous operation in demanding HVACR applications.
• Direct Replacement: Matches factory footprints and wiring harnesses for a faster "plug-and-play" installation on the job site.

Common Questions

Which water heater models use the 100077872?
This control is typically found in GSW, A.O. Smith, and Lochinvar atmospheric gas water heaters. Always verify your specific serial number as the 52720 board is model-specific and not a universal generic module.

What are the symptoms of a failing GSW 52720 control?
Common indicators include the hot surface ignitor failing to glow, the gas valve not receiving 24V during the ignition trial, or the system locking out immediately after a successful flame is established.

Can I use this board for a spark-to-pilot system?
No. The 100077872 is designed specifically for hot surface ignition systems. It provides the timed 120V output required for HSI elements and will not function with spark ignition electrodes.

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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.