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Lennox

OEM Lennox TrueSteam Water Level Sensor Assembly — Y3739

SKU: LNX-Y3739 Brand: Lennox
$24.95 $34.95

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Texas CMBL #19328542014
SAM.gov Registered
Govt POs Accepted

The Lennox Y3739 (OEM reference 50027998-002) is a genuine water level sensor assembly engineered specifically for Lennox TrueSteam whole-home humidifiers, monitoring water levels to ensure safe and efficient steam generation. A faulty water level sensor can cause your TrueSteam humidifier to shut down unexpectedly, produce error codes, fail to generate steam, or overflow due to improper water level detection. This OEM Lennox replacement part restores proper humidifier function and is designed to meet original factory specifications for compatible TrueSteam humidifier models.

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 Sensor fit my Lennox OEM Lennox TrueSteam Water Level Sensor Assembly — Y3739?
Yes. This is the factory-specified OEM sensor for the Lennox OEM Lennox TrueSteam Water Level Sensor Assembly — Y3739. 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 sensor on my Lennox OEM Lennox TrueSteam Water Level Sensor Assembly — Y3739?
Difficulty: Easy (10–15 min)
Step 1: Turn off power/gas. Step 2: Open furnace panel. Step 3: Locate flame sensor rod near burners. Step 4: Remove single mounting screw. Step 5: Clean rod with 400-grit sandpaper until shiny (or replace). Step 6: Reinstall and tighten. Most common furnace repair — saves $150–$300 vs technician.
My furnace lights then shuts off after a few seconds. Why?
Furnace lights then shuts off after 3–10 seconds = dirty flame sensor in 90% of cases. The sensor can’t detect flame through oxidation buildup. Fix: clean with 400-grit sandpaper (free, 15 min). If cleaning doesn’t work, replace the sensor.
Is this sensor 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 sensor?
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.
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Mike Rivera
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