Description
The Lennox 20K55 is an OEM replacement rollout switch designed to protect your furnace from hazardous flame rollout conditions. When burner flames extend beyond their normal boundaries — due to a cracked heat exchanger, blocked flue, or insufficient combustion air — this safety switch trips at 150°F to shut down the burner and prevent damage or injury.
How It Works
The rollout switch is a thermal safety device mounted near the burner assembly. Under normal operating conditions, the switch remains closed and allows the furnace to run. If flame rollout is detected and the switch surface reaches the 150°F trip threshold, the switch opens the control circuit, cutting power to the gas valve and shutting down the heating cycle. This protects the heat exchanger, wiring, and surrounding components from heat damage.
Key Features
- OEM Lennox replacement part — ensures proper fit and function
- 150°F trip temperature for accurate flame rollout detection
- Manual or auto-reset design provides a positive safety lockout
- Designed for use in Lennox furnace applications
- Helps protect heat exchangers, wiring, and cabinetry from flame damage
- Easy drop-in replacement for qualified HVAC technicians
Specifications
- SKU: 20K55
- Brand: Lennox
- Type: Rollout Switch (Thermal Safety Cutout)
- Trip Temperature: 150°F
- Application: Lennox Furnaces
Installation Notes
Always follow the furnace manufacturer’s service manual when replacing a rollout switch. Before replacing the switch, diagnose and correct the root cause of the rollout condition — such as a restricted flue, dirty burners, or a cracked heat exchanger. Failure to address the underlying issue may cause the new switch to trip again or result in unsafe operation.
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