Description
The Lennox 51W91 is an OEM replacement pressure switch engineered for precise draft and airflow monitoring in Lennox heating systems. With a calibrated setpoint of -0.95″ water column (w.c.) and single-pole, single-throw (SPST) switching action, this switch provides dependable protection against unsafe operating conditions such as blocked flue passages or inducer motor failure.
Key Features
- OEM Lennox replacement pressure switch — SKU 51W91
- Setpoint: -0.95″ w.c. (water column)
- Switch type: SPST (Single-Pole, Single-Throw)
- Dual 1/4″ barb port connections for easy hose attachment
- Monitors inducer/draft pressure to verify safe furnace operation
- Helps prevent furnace operation under blocked flue or inducer failure conditions
- Direct OEM replacement for compatible Lennox furnace models
How It Works
The pressure switch senses negative pressure generated by the inducer blower during furnace operation. When the measured pressure falls outside the rated setpoint of -0.95″ w.c., the SPST contacts open, signaling the control board to shut down the ignition sequence. This safeguard protects against incomplete combustion and carbon monoxide risks.
Installation
The dual 1/4″ barb connections allow straightforward hose routing to the inducer housing or collector box ports. Always verify compatibility with your specific Lennox furnace model before installation, and consult the equipment service manual for proper wiring and mounting procedures.
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