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The genuine OEM Lennox 50F84 pressure switch is a safety device that confirms the draft inducer is producing adequate airflow before the furnace allows the burners to ignite. By sensing negative pressure in the venting system, it prevents the unit from firing when a blocked flue or failed inducer could cause dangerous combustion conditions.
Common failure symptoms: A faulty 50F84 can cause the furnace to lock out, short-cycle, or refuse to light, often accompanied by a flashing error code on the control board. Stuck-open or stuck-closed switches, cracked hoses, and clogged pressure ports are frequent culprits behind intermittent no-heat problems.
Why OEM matters: Pressure switches are calibrated to a specific trip point measured in inches of water column, and that setpoint must match your Lennox furnace exactly. An incorrectly rated aftermarket switch may nuisance-trip or, worse, fail to protect the system. The OEM 50F84 arrives with the correct calibration and fittings for a safe, code-compliant repair of your Lennox equipment.