Lennox 57W78 - (R45695-003) Pressure Switch – OEM Air Pressure Safety Control for Gas Furnaces
The Lennox 57W78 (R45695-003) Pressure Switch is a factory-original replacement part engineered to maintain safe and efficient operation of your Lennox heating system. This air pressure switch is a vital safety control that ensures the furnace inducer fan is working properly and that the combustion air is vented correctly before ignition occurs. It helps prevent unsafe operating conditions such as blocked flues or inadequate airflow, automatically shutting down the burner if system pressure falls outside of acceptable levels.
Product Features:
- Precision-Calibrated Switch Point – Responds to predetermined pressure levels to signal proper venting and system readiness before allowing ignition.
- Fail-Safe Safety Mechanism – Prevents burner operation if air pressure conditions are unsafe, helping to avoid flame rollout or carbon monoxide issues.
- OEM Part by Lennox – Designed and manufactured by Lennox to meet original equipment specifications for form, fit, and function.
- High Reliability – Built with high-quality materials to ensure dependable long-term performance even under demanding operating conditions.
- 90° Quick-Connect Terminals – Simplifies installation and maintenance with standard terminal connectors.
Technical Specifications:
- Part Number: 57W78
- Replaces: R45695-003
- Function: Negative pressure switch for induced draft systems
- Mounting Style: Bracket-mounted with integrated ports
- Terminal Type: 90° quick-connect
- Application: Gas furnaces requiring pressure verification for safe ignition
- Operating Range: Factory-set actuation pressure (verify system requirements before replacement)
Common Applications:
This pressure switch is commonly found in various Lennox high-efficiency gas furnaces, including models with induced draft blower assemblies. It ensures the inducer fan has created enough negative pressure in the combustion chamber to safely ignite the burners.
Compatibility Note:
Always cross-reference with your unit’s model and part number or consult your service manual to confirm compatibility before purchase.
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