Lochinvar & A.O. Smith 100166258 Pressure Switch

The Lochinvar & A.O. Smith 100166258 Pressure Switch is a critical safety component designed for precise combustion air monitoring in high-efficiency systems. This 1.35"wc SPDT Pressure Switch functions as a pneumatic prover, ensuring the inducer fan generates sufficient static pressure before allowing the ignition sequence to proceed. As the verified OEM replacement for PRS3428 and PRS2428, this part maintains the original equipment’s narrow operating tolerances and response times, preventing dangerous unburned gas buildup or "no-heat" calls caused by fluctuating vent pressures.

Built for the Lochinvar Energyrite ER152-402 series and various A.O. Smith water heater models, this Single Pole Double Throw (SPDT) switch provides versatile wiring configurations for both normally open and normally closed circuits. It is engineered to withstand the demanding conditions of mechanical rooms, featuring a durable diaphragm that resists fatigue over thousands of cycles. For technicians troubleshooting a 3-flash diagnostic code or chronic ignition failure, replacing a drifted switch with this genuine 100166258 air pressure switch restores system reliability and ensures the pressure differential remains within the factory-specified 1.35 inch water column setpoint.

• Direct OEM Compatibility: Engineered as the exact replacement for PRS3428, ensuring a drop-in fit without needing bracket modifications.
• Reliable Proof of Flow: Calibrated at 1.35" WC to accurately detect venting obstructions or inducer motor performance drops.
• SPDT Versatility: The Single Pole Double Throw design allows for integration into complex control strings requiring specific circuit feedback.
• Durable Construction: High-grade materials designed to handle the heat and moisture common in Lochinvar Energyrite ER pool heaters and water heater exhaust paths.

• How do I diagnose a failing Lochinvar 100166258 switch? Use a digital manometer to check the actual pressure at the tap; if the pressure exceeds 1.35" WC but the switch fails to close (check continuity with a multimeter), the internal diaphragm has likely failed.
• Can this switch replace other water column ratings? No. Pressure switches are safety-rated devices; using a switch with a different water column (WC) rating than the factory spec can lead to unsafe combustion or constant lockout.
• What causes a "Pressure Switch Failed Open" error? Common culprits include blocked vent pipes, a cracked pressure sensing tube, a failing inducer motor, or a clogged condensate drain in condensing units.

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.