Industrial-Grade Construction: Built to withstand high-cycle environments and fluctuating plenum temperatures

investigate airflow issues like a clogged filter or a failing blower motor

for high-pressure steam over 150 PSI

This 270 degree furnace switch functions as a NC (normally closed) limit that opens when excessive heat is detected outside the combustion chamber

High Current Rating: Supports a 10-Amp contact rating

Lennox 21L99 Flame Sensor Industrial-Grade Construction: Built to withstandProfessional grade Lennox 21L99 Flame Sensor is a critical OEM replacement part designed to maintain pilot and burner safety through precise flame rectification. As a veteran preferred component, this sensor is engineered to monitor the furnace flame and provide the necessary DC microamp signal to the control board, ensuring the gas valve remains energized only when a safe ignition is confirmed. It serves as a direct OEM replacement for the Lennox