Lochinvar & A.O. Smith 100109877 Pressure Switch

The Lochinvar & A.O. Smith 100109877 Pressure Switch is a critical safety component designed for high-efficiency commercial boilers and water heaters. This SPST pressure switch (Single-Pole Single-Throw) is engineered to monitor low gas pressure conditions, typically calibrated at a 5.2" WC set point to ensure the system operates within safe manifold parameters. As an authentic OEM replacement part, it provides a direct fit for models including the Lochinvar Power-Fin and A.O. Smith CGN series, replacing legacy part numbers 191149-5 and 9004475215. For technicians, this switch is vital for preventing combustion instability or equipment damage caused by insufficient fuel supply. Its robust construction facilitates precise electrical continuity during the ignition sequence, making it a standard requirement for maintaining HVAC system safety and peak thermal efficiency in demanding commercial environments.

• Precise Low Gas Sensing: Calibrated to detect pressure drops below 5.2" WC, preventing lean-burn conditions.
• OEM Compatibility: Guaranteed fit for Lochinvar and A.O. Smith commercial water heaters and boilers.
• Enhanced System Safety: Automatically interrupts the 24V control circuit to prevent hazardous operation.
• Durable SPST Configuration: Built for high-cycle reliability in commercial boiler rooms.
• Simplified Installation: Designed with standard terminals for rapid field-service replacement by contractors.

What are the symptoms of a failing 100109877 pressure switch?
A faulty switch often triggers a "Low Gas Pressure" lockout on the control module or prevents the inducer/blower sequence from advancing to ignition.

Is this switch compatible with LP (Propane) systems?
Yes, this switch is utilized as a safety interlock for both natural gas and propane systems, though verify the specific inches water column requirements of your appliance before installation.

Does this part replace the 9004475215?
Yes, the 100109877 is the official updated service part for the 9004475215 and 191149-5 numbers.

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.