Description
Lennox 49L90 Pressure Switch Overview
Keep your Lennox furnace or air handler running safely and efficiently with the Lennox 49L90 Pressure Switch. Engineered as a direct OEM replacement, this pressure switch monitors draft and combustion airflow to protect your system from unsafe operating conditions — shutting down the burner if proper pressure is not maintained.
Key Features
- OEM Lennox replacement pressure switch — SKU 49L90
- Set point: 0.47″ water column (“wc)
- SPST (Single-Pole, Single-Throw) switching action
- 1/4″ barb port connection for easy hose attachment
- Designed for use in Lennox gas furnaces and related HVAC equipment
- Monitors inducer/draft pressure to ensure safe combustion airflow
- Helps prevent furnace operation under unsafe pressure conditions
Application
The 49L90 pressure switch is a critical safety component in Lennox furnace systems. It senses the negative pressure created by the inducer blower motor and confirms that adequate draft is present before allowing the ignition sequence to proceed. If pressure falls outside the acceptable range, the switch opens the circuit, preventing unsafe burner operation.
Why Choose the Lennox 49L90?
- Direct OEM fit for compatible Lennox furnace models
- Ensures proper combustion safety and system reliability
- Simple 1/4″ barb connection for quick hose installation
- Helps maintain manufacturer warranty compliance
- Trusted Lennox quality for long-term performance







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