OEM Lennox Flame Rollout Switch — 57W75

The genuine OEM Lennox 57W75 flame rollout switch is a critical safety device installed on the burner assembly of Lennox gas furnaces. It continuously monitors for flames that escape ("roll out") from the combustion chamber — a condition caused by blocked heat exchangers, cracked exchangers, or restricted flue venting. When the switch senses excessive heat outside the burner box, it instantly interrupts power to the gas valve and shuts the furnace down to prevent fire and carbon-monoxide hazards.

Common failure symptoms: The furnace lights briefly then shuts off on a lockout, the blower runs but there is no sustained heat, or the control board reports a rollout or limit fault. Over time repeated heat cycling can trip the switch permanently or cause it to fail open, leaving the furnace unable to fire.

Why OEM matters: The Lennox 57W75 is calibrated to the exact trip temperature and manual-reset specification your furnace was engineered around. Generic substitutes with the wrong set point can nuisance-trip or, worse, fail to protect the system. Installing the factory-matched part restores proper safety response and keeps your Lennox equipment operating within its rated limits.