Lochinvar & A.O. Smith 100277799 Probe

The Lochinvar & A.O. Smith 100277799 Probe is a critical safety component engineered for precision low water cut off (LWCO) monitoring in high-efficiency commercial and residential heating systems. Designed to integrate seamlessly with the Lochinvar FBL and FBN series boilers, this probe detects the presence of water via conductivity to prevent dry-fire conditions that cause catastrophic heat exchanger failure. As a veteran technician knows, maintaining safe boiler operation depends on the reliability of the LWCO probe to signal the control board to terminate the burner circuit when levels drop below the safety threshold.

This OEM replacement part (MPN: 100277799) is essential for contractors performing boiler maintenance or emergency repairs on Lochinvar heating supplies. Its robust construction ensures long-term resistance to scale buildup and corrosion, maintaining high signal accuracy in diverse hydronic environments. Whether you are troubleshooting a water heater probe error or completing a standard system inspection, utilizing genuine A.O. Smith parts ensures professional-grade compliance with original equipment specifications.

• System Protection: Effectively prevents dry firing by ensuring the burner only activates when safe water levels are confirmed.
• Broad Compatibility: Engineered specifically for Lochinvar FBL (2500-6000) and FBN (2500-6000) series models.
• High Sensitivity: Optimized for rapid conductivity detection to minimize response latency during low-flow or leak scenarios.
• Durable Construction: Built to withstand commercial-grade temperatures and pressures within the boiler vessel.
• Easy Integration: Lightweight 0.71 lb design allows for straightforward threading and terminal connection during field replacement.

How do I test the 100277799 probe during a service call?
Technicians should check for continuity between the probe tip and the boiler ground while the tank is full. If the control board still signals a low water error despite a clean probe and proper water levels, inspect the wiring harness for breaks or high resistance.

Will this probe work with other boiler brands?
While manufactured by Lochinvar & A.O. Smith, compatibility is strictly limited to the models specified in the technical manual. Always verify your specific Lochinvar or State model number before installation to ensure the thread pitch and probe length meet internal clearance requirements.

What causes these probes to fail?
The most common failure point for a low water cut off probe is heavy mineral insulation or "foaming" in the boiler water, which can trick the sensor. Regular cleaning and water treatment are recommended to maintain the integrity of the HVAC safety control.

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.