Description
Lennox 88K90 Pressure Switch Overview
The Lennox 88K90 is a factory-specified pressure switch engineered for reliable draft and combustion air proving in Lennox heating systems. Designed as a direct OEM replacement, this switch monitors negative pressure within the venting system to confirm proper inducer operation before allowing burner ignition — a critical safety function that helps prevent unsafe furnace operation.
Key Features
- Set Point: 0.47″ water column (“wc)
- Switch Type: SPST (Single-Pole, Single-Throw)
- Port Connection: 1/4″ barb fitting for secure hose attachment
- OEM Lennox replacement part — SKU 88K90
- Designed for direct, drop-in compatibility with applicable Lennox furnace models
- Helps ensure safe furnace startup by verifying inducer draft before ignition
How It Works
The pressure switch senses the negative pressure (vacuum) created by the draft inducer motor. When the inducer establishes adequate airflow, the switch closes at the 0.47″wc threshold, signaling the control board to proceed with ignition. If proper draft is not achieved, the switch remains open and prevents the furnace from firing — protecting against flue gas spillage and unsafe combustion conditions.
Application
- Lennox gas furnaces requiring a 0.47″wc pressure switch
- Direct OEM replacement for failed or faulty pressure switches
- Suitable for residential heating system service and maintenance
Why Choose the Lennox 88K90?
Using the correct OEM pressure switch ensures your Lennox furnace operates within its designed safety parameters. The 88K90 provides the precise setpoint calibration and connection geometry needed for a reliable, code-compliant repair. Trust Jackson Systems for genuine Lennox replacement parts delivered fast.
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