OEM Lennox Flame Rollout Switch — 52M73

The Lennox 52M73 flame rollout switch is a manual-reset safety limit mounted near the burners of your Lennox gas furnace. Its job is to detect flames rolling out of the combustion chamber — an unsafe condition typically triggered by a blocked heat exchanger, restricted venting, or insufficient combustion airflow. The moment excess heat reaches the sensor, the 52M73 opens the circuit and cuts power to the gas valve, stopping the burners before damage or fire can occur.

Common failure symptoms: A failed or repeatedly tripped switch will cause the furnace to lock out, deliver no heat, or ignite briefly before shutting off. Homeowners often notice short-cycling, a persistent rollout error on the diagnostic board, or a system that simply won't stay running. Because this is a safety device, a bad switch must be replaced rather than jumped out.

Why OEM matters: The 52M73 is factory-calibrated to a precise trip temperature and terminal configuration that matches your Lennox furnace. Generic replacements with mismatched ratings risk false trips or delayed shutoff. Choosing the genuine OEM part ensures exact fit, dependable protection, and seamless compatibility with your Lennox system.