OEM Lennox Burner Box Assembly — 26L74
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The genuine OEM Lennox 26L74 burner box assembly (factory reference LB-90884) houses and positions the burners that ignite and mix gas with combustion air in your Lennox furnace. It maintains precise burner alignment relative to the igniter, flame sensor, and heat exchanger inlets, ensuring a stable, correctly shaped flame and complete, efficient combustion every heating cycle.
Common failure symptoms: Heat, soot, and thermal cycling can cause the burner box to corrode, warp, or accumulate debris that disrupts the burner pattern. Symptoms include delayed or rough ignition, flame rollout, yellow or lazy flames instead of crisp blue, flame-sensor lockouts, popping or booming on startup, and the furnace failing to reach temperature.
Why OEM matters: The 26L74 is built to the exact dimensions and burner spacing Lennox engineered for safe combustion and proper flame travel into the heat exchanger. Because burner geometry is directly tied to safe ignition and clean combustion, an aftermarket substitute can misalign the flame and create carbon-monoxide or rollout hazards. The factory OEM assembly guarantees correct fit and safe, dependable furnace operation.
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