Description
The Carrier HH18HA217 is an OEM replacement high-limit switch designed to protect furnaces and heating systems from dangerous overheating conditions. Carrying the L240-50F designation, this limit switch is engineered to open the control circuit at 240°F and features a 50°F differential, allowing the switch to automatically reset (close) once the temperature drops back to approximately 190°F — helping restore normal furnace operation without manual intervention.
How It Works
The high-limit switch continuously monitors heat exchanger or plenum temperatures. If airflow is restricted — due to a dirty filter, blocked vent, or failed blower — temperatures rise beyond safe levels. The HH18HA217 responds by interrupting the burner circuit, preventing heat exchanger damage, carbon monoxide risk, and potential fire hazards. Once temperatures fall within the safe operating range, the switch automatically resets and allows the system to resume normal operation.
Key Features
- OEM Carrier replacement part — ensures proper fit and function
- Opens at 240°F to shut down burner during overheat conditions
- 50°F differential — auto-resets at approximately 190°F
- Protects heat exchanger from thermal stress and damage
- Helps prevent carbon monoxide risks associated with overheating
- Direct replacement for Carrier and compatible Bryant/Payne systems
Application
The HH18HA217 limit switch is a direct OEM replacement for select Carrier, Bryant, and Payne gas furnaces. Always verify compatibility with your specific furnace model before installation. Consult the equipment service manual for proper mounting location and wiring.
Specifications
- Part Number: HH18HA217
- Type: High-Limit Switch
- Designation: L240-50F
- Open (Trip) Temperature: 240°F
- Differential: 50°F
- Reset Temperature: ~190°F
- Reset Type: Automatic
- Brand: Carrier







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