Lochinvar & A.O. Smith 100208393 Pressure Switch

When you are troubleshooting a no-heat call on a Lochinvar or A.O. Smith high-efficiency unit, the Lochinvar & A.O. Smith 100208393 Pressure Switch is often the gatekeeper for the combustion sequence. This OEM air pressure switch is calibrated to a specific set point of 6.20" WC, ensuring that the induced draft blower is moving enough air to support safe combustion before the gas valve is energized. As an HVAC air pressure switch replacement, this part is critical for monitoring the air pressure ratios within the heat exchanger and venting system. If the system detects an airflow obstruction or a venting blockage, this switch will open and lock out the ignition control to prevent dangerous conditions like incomplete combustion or CO leakage. Built for professional-grade HVAC pressure monitoring, this component is a direct fit for compatible boilers and water heaters, providing the precise differential pressure sensing required for modern condensing equipment.

• Precise 6.20" WC Set Point: Factory-calibrated for exact induced draft blower performance verification.
• Enhanced Safety Logic: Acts as a safety lockout switch to prevent operation during flue blockage or fan failure.
• Direct OEM Fit: Simplifies HVACR equipment maintenance by matching original mounting footprints and hose connections.
• Rugged Housing: Designed to withstand the thermal cycles and moisture common in high-efficiency condensing boilers.

How do I test if the pressure switch is failing?
Using a digital manometer, verify that the blower is pulling at least 6.20" WC. If the pressure is sufficient but the switch remains open (check with a multimeter for continuity), the internal diaphragm or contacts have likely failed and the part needs replacement.

Will this switch fix a "Pressure Switch Stuck Open" error code?
If your manometer readings are within spec but the board still shows a fault, this replacement air pressure switch is the correct fix. However, always inspect the pressure switch tubing for cracks or moisture buildup first.

Is this compatible with both Lochinvar and A.O. Smith models?
Yes, as an OEM universal part (100208393 / PRS2054), it is the standard combustion air prover for various high-efficiency commercial and residential water heating platforms from both brands.

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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.