Lochinvar & A.O. Smith 100208403 Pressure Switch

The Lochinvar & A.O. Smith 100208403 Low Gas Pressure Switch is a critical safety component designed for high-efficiency commercial and residential boilers and water heaters. As a direct replacement for PRS2702 and PRS2702K, this switch ensures that the burner only initiates when the minimum required fuel pressure is available at the gas train inlet. Operating with a fixed setpoint of 2.8" W.C., it prevents unstable combustion and potential flame rollout caused by insufficient gas velocity at the orifices. This LGPS features normally open contacts that close upon sensing adequate pressure, integrating seamlessly into the 24VAC safety string of Lochinvar Copper-Fin and PFN500 models. By monitoring supply pressure before the automatic shutoff valves, it protects the heat exchanger from damage associated with low-input firing. The rugged diaphragm construction provides reliable HVAC part replacement performance in demanding mechanical rooms, maintaining system integrity and preventing hazardous re-ignitions.

• Direct Compatibility: Identical to legacy part numbers PRS2702 and PRS2702K for drop-in installation in existing gas trains.
• Critical Safety Logic: Prevents the ignition sequence if gas pressure falls below the 2.8" W.C. threshold, protecting the burner assembly.
• Veteran-Grade Durability: Engineered to withstand the frequent cycling of commercial boiler gas pressure switches.
• Simplified Troubleshooting: Standard two-terminal design allows for rapid continuity testing during routine maintenance or low gas pressure lockout diagnostics.

Common Questions

What causes a 100208403 switch to trip?
A trip is typically caused by a drop in supply pressure below 2.8" W.C., often resulting from an undersized gas line, a faulty regulator, or high demand from other appliances on the same manifold.

How do I test the functionality of this gas pressure switch?
With the gas supply on, use a digital manometer to verify the inlet pressure is above the setpoint. Check for continuity across the terminals; the switch should be closed if the pressure is adequate.

Is this an automatic or manual reset switch?
The 100208403 is an automatic reset model that will re-close the safety circuit once the gas pressure rises above the setpoint plus the internal differential.

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.