OEM Lennox Pressure Switch w/ Bracket — 11U67

The genuine OEM Lennox 11U67 is a furnace air pressure (draft) switch supplied with its mounting bracket. It monitors the negative pressure created by the inducer motor and confirms that the venting system is clear before the control board allows ignition — a mandatory safety interlock that prevents the furnace from firing if combustion gases cannot vent properly.

Common failure symptoms: When the 11U67 fails or its diaphragm sticks, the furnace typically runs the inducer motor but never ignites, locking out on a pressure-switch fault. You may see error codes for an open or stuck-closed switch, short-cycling, or a furnace that starts then shuts down repeatedly. Cracked hoses, a corroded switch body, or a switch that won't close on adequate draft all point to replacement.

Why OEM matters: Pressure switches are calibrated to a specific trip point (in inches of water column) matched to your furnace's inducer and venting design. Installing a genuine Lennox 11U67 with the correct bracket guarantees the exact set point and secure mounting the appliance was certified with, so draft is proven accurately and the safety circuit works as intended. A mismatched aftermarket switch can allow unsafe firing or cause endless nuisance lockouts. Restore reliable, safe ignition with the OEM 11U67.