Lochinvar & A.O. Smith 100208383 Pressure Switch

The Lochinvar and A.O. Smith 100208383 Pressure Switch is a critical safety component designed for high-efficiency water heaters and boiler systems. This SPST (Single Pole Single Throw) switch is calibrated to a 5.30" WC (Water Column) set point, ensuring precise monitoring of combustion blower performance and venting pressure. Often referenced by legacy part numbers PRS20020 and PRS20020K, this OEM replacement pressure switch ensures the system only initiates the ignition sequence when proper airflow is established. For technicians servicing Lochinvar Knight or A.O. Smith Cyclone models, maintaining the integrity of the differential pressure sensing circuit is vital for preventing nuisance lockouts and ensuring HVAC safety compliance. This direct-fit sensor utilizes a robust diaphragm construction to withstand the thermal cycling typical of commercial and residential high-recovery environments. Proper installation requires verifying the tubing connections are clear of moisture or debris to ensure accurate WC pressure settings and reliable equipment uptime.

• Precise Calibration: Factory set at 5.30" WC to meet specific manufacturer blower curve requirements.
• Universal Compatibility: Interchanges directly with PRS20020 and PRS20020K for streamlined inventory management.
• Reliable Switching: High-quality SPST contacts designed for frequent cycling in high-demand heating applications.
• System Protection: Prevents operation during venting blockages or inducer motor failure, protecting heat exchangers.

Common Service Questions

How do I troubleshoot a pressure switch open error on a Lochinvar boiler?
First, check for obstructions in the venting and ensure the inducer motor is reaching full RPM. Use a manometer to verify if the actual pressure exceeds the 5.30" WC set point of the 100208383 switch. If the pressure is sufficient but the switch remains open, the internal diaphragm or contacts may have failed.

Can I use a pressure switch with a different WC rating if this is out of stock?
No. HVAC safety circuits rely on specific pressure thresholds to ensure proper air-to-fuel ratios. Installing a switch with an incorrect rating can lead to incomplete combustion, carbon monoxide production, or premature component failure.

What causes these switches to fail prematurely?
The most common causes are moisture accumulation in the sensing tubes, cracked silicone tubing, or debris entering the pressure ports, which can impede the diaphragm movement.

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.