OEM Lennox Flame Rollout Switch — 52M74

The Lennox 52M74 flame rollout switch is a critical safety limit control installed on the burner assembly of your Lennox furnace. It continuously monitors for flames that escape or "roll out" of the burner box — a condition caused by blocked flue passages, cracked heat exchangers, or restricted combustion air. When abnormal heat is detected, the 52M74 trips instantly and shuts off the gas valve, preventing dangerous overheating and fire hazards.

Common failure symptoms: If this switch fails or nuisance-trips, your furnace may lock out, refuse to fire, or start and then shut down after a few seconds. You may also see a rollout fault code on the control board or find the furnace running cold despite calling for heat. A tripped or defective switch should never be bypassed, as it is a life-safety component.

Why OEM matters: Genuine Lennox parts are calibrated to the exact trip temperature and mounting specification your furnace was engineered for. Aftermarket substitutes with the wrong reset temperature can nuisance-trip or, worse, fail to protect the unit. Installing the OEM 52M74 guarantees correct fit, rated response, and full compatibility with your Lennox equipment.