OEM Lennox Rollout Limit Switch — 87H64

The genuine OEM Lennox 87H64 rollout limit switch (factory reference 20017401) is a critical safety control on your Lennox gas furnace. Mounted near the burner assembly, it monitors for flame rollout — a dangerous condition where flames escape the combustion chamber due to blockage or a venting problem. When it senses excessive heat, it opens the circuit and shuts down the burners to prevent damage and hazardous operation.

A tripped or failed rollout switch typically results in a furnace that ignites briefly and then shuts off, no heat, or a lockout fault at the control board. Because this is a one-time manual-reset or thermally-responsive safety device, repeated tripping often points to an underlying issue such as a restricted heat exchanger, blocked flue, or dirty burners that should be diagnosed and corrected.

Use only the OEM Lennox 87H64 to ensure the correct trip temperature, reset behavior, and terminal configuration your furnace's safety circuit depends on. Substituting a switch with a different rating can allow unsafe operation or cause nuisance shutdowns. Installing the factory-specified part preserves the built-in safety margin and keeps your equipment warranty valid.