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Lennox

OEM Lennox Multi-Range Pressure Transducer — 78M20

SKU: LNX-78M20 Brand: Lennox
$39.95 $54.95

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Texas CMBL #19328542014
SAM.gov Registered
Govt POs Accepted

The genuine OEM Lennox 78M20 is a multi-range differential pressure transducer that measures the pressure difference across a filter, coil, or duct section and converts it into an electrical signal the control board can read. This feedback lets your Lennox equipment monitor static pressure, verify airflow, and modulate blower speed for efficient, reliable operation across multiple selectable ranges.

When a pressure transducer fails or drifts out of calibration, you may see erratic blower behavior, nuisance airflow or pressure fault codes, poor dehumidification, or a system that will not stage or modulate correctly. A weak or intermittent signal can leave the control unable to confirm proper airflow.

Installing the OEM Lennox 78M20 ensures the exact pressure ranges, output signal, and port fittings the control logic expects. Aftermarket transducers may report inaccurate readings or use incompatible calibration, causing false faults and comfort problems. The factory transducer delivers precise, dependable sensing engineered specifically for your Lennox system.

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 Multi-Range Pressure Transducer — 78M20?
Yes. This is the factory-specified OEM sensor for the Lennox OEM Lennox Multi-Range Pressure Transducer — 78M20. 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 Multi-Range Pressure Transducer — 78M20?
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
HVAC Parts Specialist — Online