Description
The Lennox 15W56 is a factory-engineered pressure switch designed as a direct OEM replacement for compatible Lennox heating systems. Monitoring negative pressure in the flue and combustion air circuit, this switch helps ensure safe furnace operation by verifying that the inducer motor is functioning correctly before allowing ignition to proceed.
Key Features
- Set point: .43″ w.c. (inches water column)
- Switch type: SPST (Single-Pole, Single-Throw)
- Port connection: 1/4″ barb fitting for secure hose attachment
- OEM Lennox replacement part — SKU 15W56
- Designed for precise, repeatable pressure sensing in gas furnace applications
- Helps prevent furnace operation under unsafe draft or venting conditions
How It Works
The pressure switch monitors the negative pressure (vacuum) created by the draft inducer motor. When the inducer establishes proper airflow, the switch closes at the .43″ w.c. set point, signaling the control board that conditions are safe for ignition. If adequate pressure is not detected — indicating a blocked flue, failed inducer, or venting issue — the switch remains open and locks out ignition, protecting the heat exchanger and occupants.
Application
- Direct OEM replacement for select Lennox gas furnaces
- Suitable for residential forced-air heating systems
- Always verify compatibility with your specific Lennox model before installation
Installation Notes
- Connect the 1/4″ barb port to the inducer housing or pressure tap hose
- Ensure hose is free of cracks, kinks, or moisture blockage before installation
- Consult the furnace wiring diagram for proper SPST terminal connections
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