Lennox 15M20 Pressure Switch

The Lennox 15M20 Pressure Switch is a critical safety component designed for precise draft proving in residential and commercial furnaces and rooftop units. This OEM Lennox 15M20 switch is a single-pole, single-throw (SPST) normally open configuration that closes when it detects a pressure fall of .10"wc. Built with a 1/4" barb connection for easy hose attachment, this air proving switch ensures the combustion air inducer is pulling sufficient vacuum to vent flue gases safely before ignition is permitted. The Lennox 15M2001 is identical in form and function to the 15M20, making it a direct drop-in replacement for a wide range of Lennox, Armstrong, and Ducane equipment. This switch is rated for 5 Amps at 24VAC and features fine silver contact material for high-reliability switching in demanding thermal environments. Whether you are dealing with a furnace pressure switch lockout or performing routine maintenance, using a genuine Lennox 15M20 pressure switch ensures your system maintains factory-spec safety parameters and optimal airflow monitoring.

• Direct OEM Compatibility: Verified as an identical replacement for the 15M2001, streamlining inventory for service trucks.
• Precise 0.10" WC Setpoint: Calibrated to actuate at -0.10" water column to ensure proper draft before the ignition sequence starts.
• Durable Construction: Features SPST snap-acting contacts and a robust 1/4" hose barb for secure pneumatic connection.
• Multi-Brand Application: Widely used across Lennox, Allied, Armstrong, Concord, and Magic-Pak HVAC systems.

What causes a Lennox 15M20 pressure switch to stay open?
Typically, an open switch indicates a restricted vent pipe, a clogged condensate drain, or a failing inducer motor that cannot produce the required -0.10" WC vacuum. Always inspect the vacuum tubing for cracks or debris before replacing the hardware.

Are the 15M20 and 15M2001 parts interchangeable?
Yes, the 15M20 and 15M2001 are technically identical components sharing the exact same pressure specifications and physical footprint.

How do I test if this switch is functioning?
Using a manometer and a multimeter, you can verify the switch closes once the negative pressure reaches the .10"wc threshold. If the vacuum is present but the SPST contacts do not close, the switch is defective.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.