Lochinvar & A.O. Smith 100111120 Pressure Switch

The Lochinvar & A.O. Smith 100111120 is a high-precision .80" WC air pressure switch designed for critical safety monitoring in gas-fired water heaters and residential or commercial boilers. As a veteran technician knows, the pressure switch is the primary safety interlock that verifies the inducer motor is moving sufficient combustion air through the heat exchanger before allowing the ignition sequence to proceed. This OEM component is calibrated to trip at precisely 0.80 inches of water column, preventing hazardous conditions such as incomplete combustion or carbon monoxide buildup due to vent obstructions or blower failure.

Replacing a failing switch with this genuine 100111120 pressure switch ensures seamless compatibility with Lochinvar boilers and A.O. Smith water heaters, maintaining the factory-specified airflow logic. It is commonly utilized in models such as the PRN and PRL series to address "pressure switch failed to close" or "failed to open" error codes. This HVAC replacement part is built for durability in high-cycle environments, providing reliable contact closure for the 24V control circuit.

• OEM Precision: Factory-calibrated to .80" WC for exact safety compliance.
• Enhanced Safety: Immediately interrupts the ignition cycle if vent blockages or inducer motor issues are detected.
• Broad Compatibility: Fits various AO Smith, State, and American Water Heater models, ensuring a direct-drop replacement.
• Technical Reliability: Rugged diaphragm design resists fatigue, ensuring stable performance in fluctuating temperature conditions.

• What causes a 100111120 pressure switch to trip? Typically, this is caused by a clogged flue, a failing inducer fan, or restricted air intake pipes.
• Can I use a switch with a different WC rating? No. Using a rating other than 0.80" WC can lead to dangerous operation or frequent nuisance lockouts.
• Does this switch work with both LP and Natural Gas units? Yes, as it monitors airflow volume regardless of the fuel type used in the burner.

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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.