Lennox 63W39 .50/.85″ Two-Stage Pressure Switch

Description

The Lennox 63W39 is an OEM two-stage pressure switch engineered for precise pressure monitoring in Lennox heating systems. Designed with dual set points of 0.50″ and 0.85″ water column, this switch plays a critical role in verifying proper inducer motor operation and safe combustion airflow before allowing the burners to fire — protecting both the equipment and the occupants it serves.

Key Features

• Two-stage pressure switch with dual set points: 0.50″ and 0.85″ W.C.
• OEM Lennox replacement part — ensures compatibility and reliable performance
• Monitors inducer/draft blower operation to confirm adequate combustion airflow
• Prevents burner ignition if proper negative pressure is not established
• Helps protect heat exchanger integrity and system safety
• Direct drop-in replacement for supported Lennox furnace models

How It Works

The pressure switch senses the negative pressure (vacuum) created by the inducer motor. In a two-stage system, the switch monitors two distinct pressure thresholds — 0.50″ and 0.85″ W.C. — corresponding to the low- and high-fire stages of the furnace. If either stage fails to achieve its required pressure, the switch opens the control circuit, preventing ignition and alerting the system to a potential airflow or venting issue.

Application

• Lennox two-stage gas furnaces requiring dual-setpoint pressure monitoring
• Direct OEM replacement for failed or faulty pressure switches
• Suitable for residential and light commercial Lennox heating applications

Why Choose an OEM Pressure Switch?

Using a genuine Lennox OEM pressure switch ensures the correct pressure thresholds, connector configurations, and reliability standards are met. Aftermarket substitutes may not match the precise set points required for safe two-stage operation, potentially leading to nuisance lockouts or unsafe conditions.

Product Details

• Brand: Lennox
• SKU: 63W39
• Type: Two-Stage Pressure Switch
• Set Points: 0.50″ / 0.85″ W.C.
• Application: Gas Furnace Inducer/Draft Pressure Sensing