Description
Lennox 12W49 Pressure Switch Overview
The Lennox 12W49 is a factory-specified pressure switch engineered for precise airflow and draft monitoring in Lennox heating systems. Designed as a direct OEM replacement, this switch ensures your furnace operates safely and efficiently by verifying proper inducer and venting performance before allowing ignition to proceed.
Key Specifications
- Set Point: 1.35″ water column (“wc)
- Switch Type: SPST (Single-Pole, Single-Throw)
- Port Connection: 1/4″ barb fitting
- OEM Part Number: 12W49
- Compatible Brand: Lennox
Features & Benefits
- Direct OEM replacement for Lennox furnaces — no modifications required
- SPST switching action provides reliable open/close circuit control
- 1/4″ barb connection for secure, leak-free hose attachment
- Calibrated 1.35″ wc set point ensures accurate draft and pressure sensing
- Protects against unsafe furnace operation due to blocked flues or inducer failure
- Helps maintain system efficiency and prevents nuisance lockouts caused by worn or out-of-spec switches
Application
The Lennox 12W49 pressure switch is used in gas furnaces to monitor negative pressure created by the draft inducer blower. When the correct pressure level is achieved, the switch closes to signal the control board that safe combustion conditions exist. It is a critical safety component in the furnace ignition sequence.
Installation Notes
- Always verify compatibility with your specific Lennox furnace model before installation
- Inspect and replace hose tubing connected to the barb fitting if cracked or deteriorated
- Consult the furnace wiring diagram for proper terminal connections
- Recommended for installation by a qualified HVAC technician
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