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Lennox

OEM Lennox R44478-003 Valve-Expansion — 78L20

SKU: LNX-78L20 Brand: Lennox
$59.95 $84.95

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Texas CMBL #19328542014
SAM.gov Registered
Govt POs Accepted

The Lennox 78L20 (R44478-003) is an OEM expansion valve designed to precisely regulate refrigerant flow into the evaporator coil, maintaining proper system pressure and efficiency in Lennox HVAC systems. Common symptoms of a failing expansion valve include inconsistent cooling, ice buildup on the evaporator coil, and reduced system performance. This genuine Lennox OEM part ensures a direct-fit replacement for compatible Lennox models, restoring peak 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

Frequently Asked Questions

Does this Valve fit my Lennox OEM Lennox R44478-003 Valve-Expansion — 78L20?
Yes. This is the factory-specified OEM valve for the Lennox OEM Lennox R44478-003 Valve-Expansion — 78L20. 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 valve on my Lennox OEM Lennox R44478-003 Valve-Expansion — 78L20?
Requires licensed HVAC technician. Gas valve work involves gas lines that must meet local building codes. Improper installation risks dangerous gas leaks. Buy the part yourself to save 40–60% on markup, then have your technician install it.
What symptoms mean I need a new valve?
Common symptoms: unusual noises, intermittent operation, complete failure, or visible damage. Visit our diagnostic hub for symptom-based troubleshooting.
Is this valve 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 valve?
Always use OEM. Gas valves must match exact pressure ratings, port configurations, and safety certifications. Non-OEM gas valves can create safety hazards and may violate building codes.
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.
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Mike Rivera
HVAC Parts Specialist — Online