OEM Lennox Flame Rollout Switch — 15M42

The genuine OEM Lennox 15M42 flame rollout switch is a manual-reset safety limit control positioned near the burner box of your Lennox gas furnace. It monitors for flames or heat rolling out of the combustion area — an unsafe condition typically caused by a blocked heat exchanger, restricted flue, or inadequate combustion airflow. When it senses excessive temperature, the 15M42 opens the safety circuit and cuts power to the gas valve to protect against fire.

Common failure symptoms: The furnace ignites and then shuts off on lockout, no heat despite the blower running, or a persistent limit-circuit error at the control board. The switch can also degrade over time from thermal fatigue or corroded contacts, causing false trips even when combustion is normal.

Why OEM matters: This switch is factory-calibrated to a precise trip point specific to your furnace model. Using the exact Lennox 15M42 preserves the safety design of the appliance — an off-spec aftermarket part with a different setpoint can shut the unit down prematurely or leave it unprotected. Choose the OEM part for guaranteed fit, correct calibration, and reliable safety operation in your Lennox equipment.