Description
Lennox 75M20 Altitude-Specific Pressure Switch
The Lennox 75M20 is an OEM replacement pressure switch engineered for use in Lennox furnace systems operating at high-altitude installations. Calibrated to a set point of 0.75″ water column (w.c.), this switch is specifically designed for equipment installed between 4,501 and 7,500 feet above sea level — where lower air density requires altitude-compensated controls to ensure safe and reliable furnace operation.
Key Features
- OEM Lennox replacement pressure switch (SKU: 75M20)
- Set point: 0.75″ w.c. (water column)
- Altitude range: 4,501–7,500 ft above sea level
- Monitors inducer/draft pressure to confirm proper venting before allowing ignition
- Helps prevent unsafe furnace operation due to blocked flue, failed inducer, or inadequate draft
- Direct OEM replacement for compatible Lennox furnace models
Why Altitude-Specific Pressure Switches Matter
At elevations above 4,500 feet, reduced atmospheric pressure affects combustion air density and draft performance. A standard pressure switch calibrated for sea-level operation may not accurately reflect actual system conditions at high altitude. The Lennox 75M20 is factory-calibrated for the 4,501–7,500 ft altitude band, ensuring the furnace’s safety circuit responds correctly to real operating conditions — protecting both equipment and occupants.
Application
- Designed for Lennox gas furnaces installed at high-altitude locations
- Ideal for residential and light commercial HVAC service and replacement applications
- Consult your Lennox service documentation to confirm compatibility with your specific furnace model
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