Lochinvar & A.O. Smith 100108690 Pressure Switch

The Lochinvar & A.O. Smith 100108690 Pressure Switch is a critical safety and operational component designed for high-efficiency combustion systems. This negative pressure switch is factory-calibrated to a precise set point of -.15"wc (water column), ensuring the inducer fan is generating the specific vacuum required for a safe ignition sequence and continuous burner operation. Featuring a Single-Pole Double-Throw (SPDT) configuration, it provides versatile switching logic, allowing it to interface seamlessly with the control board to verify flue gas venting and airflow before energizing the gas valve.

Engineered for compatibility with specialized Lochinvar and A.O. Smith boilers and commercial water heaters, the 100108690 is built to withstand the rigorous cycling of modern HVAC systems. As a genuine OEM replacement part, it guarantees the exact electrical ratings and pneumatic sensitivity required to maintain system certifications and performance metrics. For technicians performing diagnostics, this -.15"wc pressure switch is the primary defense against blocked vent conditions or inducer failure, preventing the appliance from operating under hazardous air pressure differentials.

• Precise Calibration: Fixed -.15"wc set point ensures the combustion blower meets exact manufacturer specifications for flue gas evacuation.
• SPDT Logic: Reliable SPDT pressure switch design allows for "normally open" or "normally closed" circuit integration depending on the control sequence.
• OEM Compatibility: Direct fit for numerous Lochinvar and A.O. Smith boiler parts, reducing installation time and eliminating the need for field adjustments.
• Safety Compliance: Crucial for detecting blocked vent conditions and ensuring the mechanical integrity of the combustion process.

What are the symptoms of a failing 100108690 pressure switch?
Usually, the system will cycle the inducer motor but fail to initiate spark or glow at the igniter. You may see a "pressure switch stuck open" error code on the control board if the -.15"wc threshold is not met.

Can I use a universal pressure switch as a substitute?
It is not recommended. This part is calibrated to a specific negative .15" water column. Using a switch with a different set point can lead to poor combustion, nuisance lockouts, or unsafe operation.

Is this switch compatible with A.O. Smith commercial water heaters?
Yes, the 100108690 is a standard component in several A.O. Smith and Lochinvar high-recovery units. Always verify the part number against your specific model's wiring diagram.

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.