Description
The Lennox 59W39 is a genuine OEM replacement pressure switch engineered to deliver precise, dependable performance in Lennox heating systems. Designed to monitor negative pressure generated by the draft inducer, this switch protects the furnace by verifying that proper airflow and venting conditions are established before allowing the ignition sequence to proceed — a critical safety function in modern induced-draft and condensing gas furnaces.
Key Specifications
- Opening (Trip) Set Point: 0.85″ W.C.
- Reset Set Point: 1.04″ W.C.
- OEM Part Number: 59W39
- Brand: Lennox (Genuine OEM Replacement)
How It Works
The pressure switch senses the negative (vacuum) pressure produced by the draft inducer motor. When the inducer reaches the correct operating speed and airflow, the pressure differential causes the switch to close, signaling the control board to continue the ignition sequence. If the sensed pressure falls outside the acceptable range — indicating a blocked flue, failed inducer, or cracked pressure switch hose — the switch opens and locks out the furnace, preventing unsafe operation.
Why Choose a Genuine Lennox OEM Part?
- Exact-fit replacement engineered to Lennox factory specifications
- Precise calibrated set points (0.85″ W.C. open / 1.04″ W.C. reset) for reliable furnace operation
- Helps maintain system warranty compliance and original equipment performance
- Eliminates guesswork associated with aftermarket substitutes
Typical Application
- Lennox induced-draft and condensing gas furnaces
- Used as a direct OEM replacement during routine service or troubleshooting
- Ideal for HVAC technicians performing pressure switch diagnostics and replacements
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