Lennox 49L90 Pressure Switch

Ensure reliable combustion safety and system performance with the Lennox 49L90 Pressure Switch. This genuine OEM component, which is a direct replacement for Lennox 49L9001 and Honeywell IS20100-3072, is engineered specifically for Lennox furnace pressure switch applications requiring a precise .47" WC (water column) trip point. Featuring a 1/4" barb connection for secure pneumatic hosing and a single-pole single-throw (SPST) configuration, this switch monitors the negative pressure generated by the inducer motor to verify proper venting before allowing ignition. Designed for high-altitude applications up to 4500 feet, this HVAC pressure switch helps prevent nuisance trips and protects the heat exchanger from overheating due to airflow restrictions. Whether you are addressing a furnace pressure switch error code or performing a maintenance swap, this OEM part facilitates a seamless furnace pressure switch replacement for residential and light commercial equipment from Lennox, Allied, and Armstrong.

• OEM Compatibility: Seamlessly replaces Lennox 49L9001 and 49L90001 to maintain factory safety specifications.
• High-Altitude Ready: Calibrated for reliable performance in various environments, including altitudes up to 4500 feet.
• Precise Actuation: The factory-set .47" WC threshold ensures the inducer motor is moving sufficient air for safe combustion.
• Standardized Ports: Features a 1/4" barb for a quick, leak-free connection to existing pressure switch tubing.

What are the symptoms of a failing Lennox 49L90 switch?
Common signs include the inducer motor running continuously without the burners igniting, or the control board flashing a specific pressure switch fault code (typically a 2 or 3 flash code on many Lennox units). Always check for cracked tubing or blocked vent pipes before replacing the hardware.

Is the 49L90 interchangeable with the 49L9001?
Yes, the 49L90 is technically identical to the 49L9001. They share the same technical specifications, including the .47" WC set point and SPST contact configuration.

Can I use this switch in high-altitude environments?
This switch is rated for operation in altitudes from sea level up to 4500 feet. For installations above 4500 feet, always consult the specific furnace's high-altitude conversion manual to verify the required pressure setting.

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.