Description
Lochinvar & A.O. Smith 100308918 — Normally Closed Air Pressure Switch
The Lochinvar & A.O. Smith 100308918 is an OEM replacement normally closed (N.C.) air pressure switch designed to monitor and protect combustion airflow in commercial and residential water heaters and boilers. With a set point of -2″ WC (inches water column), this switch confirms that adequate negative pressure is present before allowing the burner system to operate, helping prevent unsafe combustion conditions and protecting equipment from damage.
Key Features
- OEM replacement part for Lochinvar and A.O. Smith water heaters and boilers
- Normally closed (N.C.) configuration — opens on pressure rise above set point
- Set point: -2″ WC (negative 2 inches water column)
- Monitors combustion air pressure to verify proper draft inducer operation
- Helps prevent burner ignition under unsafe airflow conditions
- Direct drop-in replacement for reliable, code-compliant serviceability
- Built for durability in demanding commercial and residential heating applications
Application
This air pressure switch is a critical safety component in gas-fired water heaters and boilers. It works in conjunction with the draft inducer blower to confirm that proper negative pressure (draft) is established before the ignition sequence proceeds. If the inducer fails or airflow is obstructed, the switch remains closed and prevents the burner from firing, protecting both the appliance and the building occupants.
Compatibility
- Designed for use with select Lochinvar and A.O. Smith water heater and boiler models
- Refer to your equipment’s service manual or parts list to confirm fitment by model number
- SKU: 100308918
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