Lochinvar & A.O. Smith 100208376 Switch

The Lochinvar & A.O. Smith 100208376 Switch is a critical safety component engineered for precision air pressure monitoring in high-efficiency condensing boilers and water heaters. As an authentic OEM replacement pressure switch, this part is calibrated to a 0.12" WC (Water Column) set point, ensuring the blower assembly maintains the necessary static pressure for safe combustion. This switch, also identified by part numbers PRS20008 and PRS20008K, is designed to detect "Low Air" conditions—labeled as Low Air After D08—effectively preventing the ignition cycle if flue gas venting or air intake is obstructed. It is a direct fit for Lochinvar Knight and A.O. Smith models, including the PBL and PBN series from 1501 to 2001. For technicians troubleshooting frequent "Air Pressure SW" lockouts, replacing the 100208376 boiler switch restores reliable differential pressure sensing, protecting the heat exchanger from improper fuel-to-air ratios and ensuring system uptime in demanding commercial or residential applications.

Key Benefits:

• Precise Pressure Sensing: Calibrated to 0.12" WC to ensure exact differential pressure monitoring within the combustion chamber.
• OEM Compatibility: Replaces obsolete parts PRS20008, PRS20008K, and 100166103 for a seamless "plug-and-play" installation.
• Enhanced Safety Logic: Integrated Low Air After D08 functionality prevents hazardous operation during venting failures or intake blockages.
• Durable Construction: Built to withstand the high-cycle demands of Lochinvar Knight boilers and professional-grade A.O. Smith water heaters.

Common Questions:

What causes a "Low Air After D08" error on a Lochinvar boiler?
This fault typically indicates that the 100208376 switch contacts are open when they should be closed. Common causes include a failing blower motor, blocked intake/exhaust piping, or a ruptured diaphragm within the air pressure switch itself.

How do I check if my 100208376 switch is faulty?
Using a manometer, verify the actual pressure at the switch's reference ports. If the system pressure exceeds the 0.12" WC set point but the switch fails to close (check continuity with a multimeter), the unit is defective and requires replacement.

Is this a direct replacement for PRS20008?
Yes, the 100208376 is the current manufacturer-approved replacement for PRS20008 and PRS20008K, maintaining identical technical specifications and electrical ratings.

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.