Lennox Primary Limit Switch F Auto Reset Boiler Safety Controls & Aquastats

Lennox primary limit switches are auto-reset furnace limit controls. They monitor heat in the heating section and act as a key safety device. If temperatures rise too high, for example from restricted airflow, the switch opens and the control shuts off the gas valve. Once the unit cools to normal operating temperature, the switch closes again on its own, so no manual reset is needed. This line is also known as a furnace limit switch, high limit switch or primary limit control.

Key Features:

• Auto-reset design recloses automatically when temperature returns to normal
• Helps protect the heat exchanger and furnace components from overheating
• Factory-calibrated temperature set point, which is not field adjustable
• Genuine Lennox replacement part for use with Lennox HVAC equipment
• Models are offered with different temperature ratings, so choose the one that matches your original part

A working primary limit switch is an important part of reliable, safe furnace operation. Replacing a worn or failed limit with the correct Lennox part helps restore normal heating cycles.