Ao Smith 100187858 Blower Prover Switch

Product Description

The AO SMITH 100187858 is a blower prover switch designed to verify inducer motor operation in gas-fired water heaters and boilers. This pressure-sensing safety control closes or opens a circuit in response to negative pressure generated by the draft inducer, confirming adequate combustion airflow before allowing the burner to ignite. Without a functioning blower prover switch, the control board will not energize the gas valve, making this component a critical safety interlock in the venting system. Installation and replacement are typically performed by licensed plumbers, HVAC technicians, or gas appliance service professionals.

The 100187858 is suited for use in gas-fired residential water heaters equipped with a powered draft inducer assembly. This switch monitors the pressure differential created during inducer operation and signals the control circuit that proper venting conditions exist before combustion begins. It is a direct replacement switch for service and maintenance situations where the original switch has failed, drifted out of calibration, or caused nuisance lockouts in the appliance control sequence.

Key Features

• Pressure-sensing safety interlock that confirms inducer airflow before burner ignition
• Designed for gas-fired water heater applications with draft inducer systems
• Prevents gas valve energization if adequate venting pressure is not detected
• OEM-style replacement for straightforward field serviceability

Compatibility

Designed as an OEM-style replacement blower prover switch for AO SMITH gas-fired water heaters equipped with draft inducer assemblies.

Installation Notes

Installation should be performed by a qualified plumber or HVAC technician familiar with gas appliance controls. Shut off gas supply and disconnect electrical power to the appliance before servicing any control components. The pressure port tubing must be securely reattached to the switch inlet after installation to ensure accurate pressure sensing. Verify the replacement switch closes and opens at the correct point in the control sequence before returning the appliance to service.

Technical Specifications

• Component Type: Blower Prover Switch

Standard Information

• Brand: AO SMITH
• Manufacturer Part Number: 100187858