Lochinvar & A.O. Smith 100208399 Pressure Switch

Professional-grade Lochinvar & A.O. Smith 100208399 Pressure Switch is a critical safety component designed for high-efficiency boilers and water heaters. As a low air pressure switch, it monitors the differential pressure within the combustion chamber to ensure the blower is moving sufficient air for safe ignition and sustained combustion. This OEM part is a direct replacement for PRS2434 and PRS2434K, as well as legacy part number 100166179. Engineered for precision, it prevents the system from firing under restricted airflow or venting conditions, protecting the heat exchanger from thermal stress and soot accumulation. Technicians will find this switch compatible with Lochinvar Knight and PBN0752-F9 series units. The 100208399 features a factory-calibrated set point, typically 5.00" WC, to maintain HVAC safety limit standards. For contractors, using this genuine Lochinvar part ensures exact boiler pressure switch mounting alignment and electrical terminal compatibility, reducing diagnostic callbacks and ensuring the Smart System control sequence initiates correctly during the pre-purge cycle.

• Ensures combustion safety by proving airflow before the gas valve is energized.
• Direct OEM replacement for PRS2434 and PRS2434K, ensuring no mounting modifications are required.
• Compatible with a wide range of Lochinvar Knight boilers and A.O. Smith water heaters.
• Critical for preventing blocked flue conditions and dangerous carbon monoxide buildup.
• Rugged construction designed to withstand the high-temperature environment of commercial mechanical rooms.

• How do I test the 100208399 pressure switch? Use a digital manometer to verify the actual atmospheric vs. induced pressure and a multimeter to check for continuity across the NO/NC terminals when the set point is reached.
• Will this fix a 'Low Air' lockout error? While often the culprit, technicians should also inspect the vent piping for obstructions and the blower motor for proper RPM before replacing the switch.
• Is this switch identical to the PRS2434K? Yes, the 100208399 is the current manufacturer part number for the discontinued PRS2434 and PRS2434K versions.

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.