Lennox 75M20 Pressure Switch R-410A By plumbing the 770-1 as

By plumbing the 770-1 as a differential pressure switch across the filter bank

allowing for CW or CCW rotation

For multi-stage applications

making it an essential component for bypass thermal expansion relief

Lennox 75M20 Pressure Switch R-410A By plumbing the 770-1 asThe Lennox 75M20 Pressure Switch is a critical safety component engineered for high altitude gas furnace applications, specifically calibrated for elevations between 4501 and 7500 feet. This OEM Lennox replacement part, also identified as 75M2001, monitors the inducer motor's static pressure to ensure the combustion air system is clear and operational before allowing the ignition sequence to initiate. With a precise fixed set point of 0. 75" WC (water