OEM Lennox Limit Switch — 56W20
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The genuine OEM Lennox 56W20 limit switch is a critical high-temperature safety control found in Lennox gas and electric furnaces. It continuously monitors the temperature inside the heat exchanger and plenum, opening the circuit to shut off the burners if the unit overheats. This protects the heat exchanger from cracking and prevents dangerous conditions caused by restricted airflow, a failed blower motor, or a clogged filter.
Common failure symptoms: When the 56W20 fails or trips repeatedly, you may notice the furnace short-cycling, the burners igniting and quickly shutting off, no heat output, or the blower running continuously. A limit switch that has weakened over time can nuisance-trip even when temperatures are normal, leaving your home cold.
Why OEM matters: Lennox engineers this limit switch to a precise trip temperature and reset threshold specific to your furnace model. Aftermarket substitutes with incorrect settings can either fail to protect the heat exchanger or cause constant nuisance trips. Installing the factory-spec 56W20 ensures accurate, reliable safety operation and preserves your Lennox equipment warranty and rated performance.
Shipping Information
- Orders placed before 3PM CST ship same business day
- Standard delivery: 2-5 business days
- Express shipping available at checkout
- Free shipping on orders over $75
- Tracking number emailed upon shipment
Return Policy
- 30-day returns on unused parts in original packaging
- Electrical parts (capacitors, contactors, control boards) are final sale once installed
- Email info@nationalhvacparts.com to initiate a return
- Refunds processed within 5-7 business days