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 Two-Way On-Off Low Voltage 3/4" Sweat 24V NC Zone Valve — 33N99

SKU: LNX-33N99 Brand: Lennox
$59.95 $84.95

OEM Guaranteed

Same-Day Ship

30-Day Returns

Secure Checkout

Texas CMBL #19328542014
SAM.gov Registered
Govt POs Accepted

The Lennox 33N99 is an OEM two-way, normally closed (N.C.), low-voltage zone valve designed for 3/4" sweat connections operating on 24V AC power. This valve controls the flow of hot or chilled water in zoned hydronic heating and cooling systems, opening on demand from a thermostat signal to deliver precise comfort to individual zones. Symptoms of a failed zone valve include a zone that never heats or cools, a zone that stays on continuously, or audible clicking without water flow. This Lennox OEM replacement valve is compatible with Lennox hydronic zoning systems and select multi-zone applications requiring 3/4" sweat fittings.

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 Two-Way On-Off Low Voltage 3/4" Sweat 24V NC Zone Valve — 33N99?
Yes. This is the factory-specified OEM valve for the Lennox OEM Lennox Two-Way On-Off Low Voltage 3/4" Sweat 24V NC Zone Valve — 33N99. 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 Two-Way On-Off Low Voltage 3/4" Sweat 24V NC Zone Valve — 33N99?
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.
Home Shop Search Account Cart
Fitment Guaranteed
MR
Mike Rivera
HVAC Parts Specialist — Online