Description
The Lochinvar & A.O. Smith 100187858 is a 1.0″ Blower Prover Switch designed as a direct OEM replacement for compatible Lochinvar and A.O. Smith water heater and boiler equipment. This safety switch plays a critical role in the combustion air proving sequence, confirming that the inducer blower is operating at the correct airflow level before allowing the burner to fire.
Product Overview
The blower prover switch monitors negative pressure (draft) created by the inducer blower assembly. When sufficient airflow is established, the switch closes to signal the control board that safe combustion conditions exist. If airflow is inadequate or the inducer fails, the switch remains open, preventing ignition and protecting both the appliance and occupants from unsafe operation.
Key Features
- OEM part number 100187858 — direct factory replacement
- 1.0″ rated blower prover (pressure differential) switch
- Designed for use with Lochinvar and A.O. Smith water heaters and boilers
- Monitors inducer blower airflow to prove safe combustion conditions
- Prevents burner ignition if proper draft is not established
- Helps maintain system efficiency and occupant safety
Application
- Compatible with select Lochinvar and A.O. Smith residential and commercial water heaters and boilers
- Intended for use by qualified HVAC and plumbing technicians
- Refer to equipment documentation to confirm compatibility before installation
Why Replace Your Blower Prover Switch?
A faulty blower prover switch can cause nuisance lockouts, failure to ignite, or — in worst-case scenarios — unsafe burner operation. Replacing a worn or failed switch with a genuine OEM part restores reliable, code-compliant performance and extends the service life of the appliance.
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