Lochinvar & A.O. Smith 100288430 Switch

The Lochinvar & A.O. Smith 100288430 Low Air Pressure Switch is a critical safety component designed for high-efficiency condensing boilers and water heaters. As a veteran technician knows, this normally open switch is calibrated to a precise 0.75" water column (W.C.) set point. It serves as the primary "proof of airflow" for the inducer motor, ensuring that the combustion blower is creating sufficient negative pressure to safely evacuate flue gases before the ignition sequence initiates. If the diaphragm fails to sense the required vacuum pressure, the control board will trigger a lockout, preventing gas valve energization and potential hazardous exhaust buildup.

This genuine OEM 100288430 air pressure switch is a direct replacement for several Lochinvar Knight and A.O. Smith industrial models, including the PBL1302-F9 and PBN1302-F9 series. Engineered with a durable internal diaphragm and high-grade electrical contacts, it handles the rapid cycling demands of commercial and residential HVACR systems. When troubleshooting short-cycling or ignition failure, verify the pressure switch hose for cracks or moisture and ensure the vent termination is clear of obstructions before replacing this component.

• Critical Safety Sync: Prevents the gas valve from opening unless the inducer draft is verified at 0.75" W.C.
• OEM Precision: Guaranteed compatibility with Lochinvar PBL/PBN units, eliminating the calibration risks of universal "will-fit" switches.
• Rugged Construction: Designed to withstand the heat and moisture typical of condensing furnace environments.
• Fast Diagnostics: Standard spade terminals facilitate quick continuity testing with a multimeter during service calls.

How do I know if my 100288430 switch is faulty?
Check for error codes indicating "Pressure Switch Stuck Open." Use a manometer to verify the inducer is pulling more than 0.75" W.C. If the draft is sufficient but the switch fails to show continuity, the diaphragm or internal contacts have likely failed.

Can I adjust the pressure setting on this switch?
No. This is a factory-calibrated safety device. Tampering with the set point can lead to incomplete combustion or delayed ignition. Always replace with the exact OEM specification.

Why is there water in my pressure switch tubing?
In high-efficiency 90%+ units, condensation can back up if the inducer housing or flue is improperly pitched. Drain the lines and check the condensate trap before installing the new switch to prevent repeat failure.

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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.