Same-day shipping before 3PM CST · 35,000+ OEM Parts · Texas CMBL & SAM.gov Registered · Government POs Accepted

Menu

Home Shop All Account Cart

IMAGE COMING SOON

Lennox

OEM Lennox 103623-06 Gas Burner Orifice Nat (.0935) — 18K21

SKU: LNX-18K21 Brand: Lennox
$49.95 $69.95

OEM Guaranteed

Same-Day Ship

30-Day Returns

Secure Checkout

Texas CMBL #19328542014
SAM.gov Registered
Govt POs Accepted

The Lennox 18K21 (OEM part 103623-06) is a genuine natural gas burner orifice with a .0935 drill size, precision-manufactured to control the gas flow rate entering the burner in compatible Lennox furnace models. A damaged or obstructed orifice can cause symptoms such as rough ignition, yellow-tipped flames, carbon buildup, or poor heating efficiency. Replacing it with this authentic Lennox OEM part guarantees the correct gas-to-air ratio and safe, consistent burner 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

Frequently Asked Questions

Does this Burner Assembly fit my Lennox OEM Lennox 103623-06 Gas Burner Orifice Nat (.0935) — 18K21?
Yes. This is the factory-specified OEM burner assembly for the Lennox OEM Lennox 103623-06 Gas Burner Orifice Nat (.0935) — 18K21. It is a direct drop-in replacement that fits without modification. Always verify the model number on your equipment nameplate before ordering.
How do I replace the burner assembly on my Lennox OEM Lennox 103623-06 Gas Burner Orifice Nat (.0935) — 18K21?
Refer to your equipment service manual for model-specific steps. General approach: turn off power, photograph connections, remove old part, install new part, restore power and test. For gas components, hire a licensed technician. Email info@nationalhvacparts.com for guidance.
What symptoms mean I need a new burner assembly?
Common symptoms: unusual noises, intermittent operation, complete failure, or visible damage. Visit our diagnostic hub for symptom-based troubleshooting.
Is this burner assembly compatible with Bryant or Payne too?
Many Lennox parts are cross-compatible with Bryant and Payne since all three brands are manufactured by Carrier Global Corporation. The same physical part is often used across brand labels with different model numbers. To verify: check your Bryant or Payne equipment service manual for cross-compatible part numbers, or email info@nationalhvacparts.com with your model number.
Should I use OEM or aftermarket for my Lennox burner assembly?
OEM recommended for reliability and warranty compatibility. OEM parts match exact factory specifications for proper fit, performance, and safety. While aftermarket alternatives cost less upfront, the risk of improper fit and reduced lifespan usually makes OEM the better value long-term.
How fast does National HVAC Parts ship?
Orders placed before 3:00 PM CST ship the same business day. Standard delivery is 2–5 business days anywhere in the continental United States. Express shipping available at checkout. We ship from Houston, TX to all 50 states. 30-day return policy on all parts.
Home Shop Search Account Cart
Fitment Guaranteed
MR
Mike Rivera
HVAC Parts Specialist — Online