Supco SHL503 Plenum Limit Switch L190-40F

The Supco SHL503 Plenum Limit Switch is a temperature protection control part used in furnace sections to prevent overheating conditions in HVAC systems. It has a 190F set point at 40F, helping regulate excessive air temperature during heating cycles. It is placed in gas furnace assemblies, and it monitors discharge or plenum heat levels and interrupts burner operation. It is used to ensure thermal protection, maintain airflow temperatures, and support consistent furnace operation under normal and high-load conditions in the system.