Lochinvar & A.O. Smith 100110806 Switch

The Lochinvar & A.O. Smith 100110806 BTH 400 Blower Prover Switch is a critical safety component designed specifically for Cyclone BTH-400 commercial water heaters. This normally open, positive air pressure switch acts as a safety interlock, verifying that the combustion air blower is generating sufficient airflow before the ignition sequence is allowed to proceed. By "proving" the blower's operation, it prevents the gas valve from opening if exhaust gases cannot be safely vented, mitigating the risk of hazardous flue gas accumulation. As a direct replacement for the obsolete A.O. Smith 9006002215, this genuine OEM part ensures factory-spec performance and precise calibration for high-input natural gas and propane systems.

For technicians troubleshooting a "Blower Prover Open" error, this 100110806 switch is the primary suspect when the blower is running but ignition fails. It features a durable diaphragm-actuated design that reacts to pressure changes within the blower housing. Built to withstand the high-demand cycles of commercial HVAC and water heating systems, this switch is essential for maintaining the operational integrity and safety of Lochinvar and A.O. Smith Cyclone units. Ensure the sensing tube is clear of condensation or debris during installation to prevent premature trip cycles.

Key Benefits:

• Precise Pressure Sensing: Calibrated specifically for the BTH-400 blower assembly to ensure accurate airflow verification.
• OEM Compatibility: Guaranteed fit for Lochinvar & A.O. Smith BTH-400 models, replacing part number 9006002215.
• System Safety Interlock: Prevents gas burner ignition unless proper exhaust drafting is established.
• Contractor-Grade Durability: Engineered for long-term reliability in high-cycle commercial mechanical rooms.

Common Questions:

What causes a "Blower Prover Open" error on a Cyclone BTH-400?
This code usually indicates that the 100110806 switch has not closed despite the blower being energized. Common causes include a faulty switch diaphragm, a cracked or blocked sensing tube, or a restriction in the vent/intake piping that prevents the blower from reaching the required pressure setpoint.

Can I jumper the blower prover switch to test the heater?
No. The combustion control board (CCB) performs a diagnostic check to ensure the switch contacts are normally open before the blower starts. If the switch is bypassed or stuck closed, the system will lockout for safety reasons.

Does this switch include the sensing tubing?
Typically, this is the switch component only. Pro-tip: Always inspect the 1/4-inch tubing for cracks or moisture when replacing the switch, as these issues often mimic a failed pressure 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.