Lochinvar & A.O. Smith 100110887 Switch

The Lochinvar & A.O. Smith 100110887 Blocked Outlet Switch is a critical safety component engineered for BTH 400A Series 100/101 gas water heaters and compatible Lochinvar Knight boilers. This normally closed switch is calibrated to a 1.39-inch water column, providing precise monitoring of the exhaust vent airflow. Designed to detect back-pressure or obstructions in the flue, it serves as a fail-safe by interrupting the 24V control circuit to the gas valve if venting is compromised. This prevents the dangerous accumulation of carbon monoxide and protects the heat exchanger from thermal stress caused by improper combustion air ratios. For technicians troubleshooting a hard lockout or a "blocked outlet" error code on the Smart System control module, this genuine OEM replacement part ensures the system returns to factory specifications. This switch is vital for maintaining the 120V/60Hz single-phase operation of high-efficiency condensing units where proper static and dynamic pressure must be maintained for safe firing.

• OEM Compatibility: Exact replacement for A.O. Smith 100110887 and equivalent part numbers, ensuring seamless fit in BTH-400A series units.
• Critical Safety Integration: Monitors for blocked flue conditions, triggering a system shutdown to prevent hazardous emissions and equipment damage.
• Precise Calibration: Factory-set at 1.39" W.C. to meet the specific airflow requirements of commercial and residential high-efficiency water heaters.
• Durable Construction: Built to withstand the corrosive environment of condensing exhaust systems, maintaining reliable signal continuity.

• What causes a blocked outlet switch to trip? Common causes include debris in the vent pipe, excessive condensate buildup due to improper flue pitch, or a failing inducer blower that cannot maintain the required pressure.
• Can I bypass this switch for testing? While used for diagnostic purposes by licensed contractors, the system must never be operated permanently without a functional 100110887 switch, as it is a primary safety limit.
• Which models utilize the 100110887? It is primarily used in A.O. Smith BTR 400A (Natural Gas and LP) and selected Lochinvar water heaters and boilers requiring a normally closed blocked outlet switch.

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.