Lochinvar & A.O. Smith 100109151 Switch

The Lochinvar & A.O. Smith 100109151 is a critical safety component designed for high-efficiency BTH (Best Tankless Hybrid) water heaters and commercial boilers. This Low Gas Pressure Switch is factory-calibrated to a 5" WC (Water Column) set point, serving as a primary sentry to ensure safe combustion cycles. In the field, this switch monitors the incoming gas supply pressure to prevent the burner from firing under insufficient pressure conditions, which can lead to unstable flames, inefficient combustion, or potential equipment damage. When the pressure drops below the calibrated threshold, the switch opens the circuit, triggering a safety lockout to protect the heat exchanger and burner assembly.

Engineered for the demands of commercial HVACR environments, the 100109151 BTH Switch provides the reliability seasoned contractors expect from OEM Lochinvar parts. Whether you are performing a gas pressure switch replacement or troubleshooting a Low Gas Pressure fault code on an A.O. Smith Cyclone or Lochinvar Armor unit, this authentic component ensures exact fitment and electrical compatibility. Integrating this switch into your preventative maintenance routine helps avoid emergency service calls caused by fluctuating supply line pressures or failing safety limits.

• Critical Safety Protection: Automatically prevents unit operation if gas pressure falls below 5" WC, protecting the system from lean combustion.
• OEM Compatibility: Designed specifically for Lochinvar and A.O. Smith water heaters, ensuring seamless integration with the existing control board.
• Enhanced Reliability: Heavy-duty construction and precise calibration reduce nuisance trips and improve long-term system uptime.
• Direct Replacement: Replaces part number 100109151 without the need for field modifications or bracket adjustments.

• What causes a "Low Gas Pressure" fault message? Typically, this indicates that the incoming gas supply has dropped below the 5" WC threshold, the gas shut-off valve is partially closed, or the 100109151 switch itself has failed and is no longer closing the circuit.
• Is this switch compatible with LP (Propane) units? While primarily used in natural gas applications, you must verify the specific manifold pressure requirements of your model, as LP systems often operate at higher pressures and may require different set points.
• Where is this switch typically located? It is usually mounted on the gas train assembly, upstream of the gas control valve, to monitor the supply pressure before it enters the combustion system.

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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.