OEM Lennox Pressure Switch — 24W51

The genuine OEM Lennox 24W51 pressure switch is a safety device that confirms your Lennox furnace has adequate draft before the ignition sequence begins. It senses the negative pressure created by the inducer motor and closes its contacts only when airflow through the heat exchanger and venting is correct, preventing the burners from firing if the flue is blocked or the inducer has failed.

A faulty or failing pressure switch commonly causes the furnace to lock out on ignition, short-cycle, or refuse to start entirely — often accompanied by a flashing fault code on the control board. Stuck-open or stuck-closed contacts and cracked sensing hoses are frequent culprits behind intermittent no-heat calls.

Choosing the OEM Lennox 24W51 ensures the switch trips at the exact pressure setpoint your furnace requires. Because this component is safety-critical, an out-of-spec aftermarket switch can allow unsafe firing or produce persistent nuisance lockouts. The factory-matched calibration guarantees proper integration with the Lennox ignition control and keeps your system operating within its designed safety parameters.