Lennox 12W49 Pressure Switch
The Lennox 12W49 Pressure Switch (Model R20558702) is a critical OEM safety component engineered for precise combustion air monitoring in Lennox gas furnaces. This SPST pressure switch is factory-calibrated to actuate at 1.35" W.C., ensuring the inducer motor generates sufficient draft for safe venting before the ignition sequence begins. Designed for professional-grade reliability, it features a standardized 1/4" barb connection for secure pneumatic tubing attachment and a durable housing built to withstand the thermal cycling typical of modern HVAC environments.
As a low-fire pressure switch, the 12W49 provides essential feedback to the control board, preventing the operation of burners under hazardous conditions such as blocked flues or failing inducer assemblies. Whether you are performing a routine service or a critical repair, using this genuine Lennox HVAC part ensures exact fitment and maintains the factory-specified safety parameters of the equipment. This component is common in high-efficiency and modulating systems where accurate static pressure sensing is paramount for system performance.
Key Benefits
- OEM Precision: Guaranteed compatibility and performance as a direct Lennox furnace part replacement.
- Enhanced Safety: Monitors 1.35" water column pressure to verify proper exhaust venting and prevent carbon monoxide risks.
- Robust Construction: Built with SPST (Single Pole Single Throw) internal contacts designed for high-cycle industrial reliability.
- Universal Barb Fitting: Includes a 1/4-inch barb connection for seamless integration with existing pressure switch hoses.
- System Stability: Specifically engineered to reduce nuisance trips while maintaining strict adherence to combustion safety protocols.
Common Questions
What causes a Lennox pressure switch to stay open?
An open circuit typically indicates the inducer motor is not creating enough vacuum, often due to a clogged vent pipe, a cracked pressure switch hose, or a blocked drainage trap in condensing furnaces. If the signal remains open despite proper vacuum, the internal diaphragm or contacts may have failed.
Is the 12W49 compatible with 80% and 90%+ efficiency furnaces?
Yes, this switch is used across multiple Lennox platforms, but it is vital to match the 1.35" W.C. actuation point found on your existing part’s label. Installing a switch with the wrong pressure rating can lead to hazardous operation or frequent system lockouts.
How do I test the Lennox 12W49 for failure?
Technicians should use a manometer to verify the system is pulling at least 1.35" W.C. and a multimeter to check for continuity across the terminals once that pressure threshold is reached. Always ensure the furnace power is disconnected before removing the SPST leads.
Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.
Original: $38.11
-65%$38.11
$13.34Lennox 12W49 Pressure Switch
The Lennox 12W49 Pressure Switch (Model R20558702) is a critical OEM safety component engineered for precise combustion air monitoring in Lennox gas furnaces. This SPST pressure switch is factory-calibrated to actuate at 1.35" W.C., ensuring the inducer motor generates sufficient draft for safe venting before the ignition sequence begins. Designed for professional-grade reliability, it features a standardized 1/4" barb connection for secure pneumatic tubing attachment and a durable housing built to withstand the thermal cycling typical of modern HVAC environments.
As a low-fire pressure switch, the 12W49 provides essential feedback to the control board, preventing the operation of burners under hazardous conditions such as blocked flues or failing inducer assemblies. Whether you are performing a routine service or a critical repair, using this genuine Lennox HVAC part ensures exact fitment and maintains the factory-specified safety parameters of the equipment. This component is common in high-efficiency and modulating systems where accurate static pressure sensing is paramount for system performance.
Key Benefits
- OEM Precision: Guaranteed compatibility and performance as a direct Lennox furnace part replacement.
- Enhanced Safety: Monitors 1.35" water column pressure to verify proper exhaust venting and prevent carbon monoxide risks.
- Robust Construction: Built with SPST (Single Pole Single Throw) internal contacts designed for high-cycle industrial reliability.
- Universal Barb Fitting: Includes a 1/4-inch barb connection for seamless integration with existing pressure switch hoses.
- System Stability: Specifically engineered to reduce nuisance trips while maintaining strict adherence to combustion safety protocols.
Common Questions
What causes a Lennox pressure switch to stay open?
An open circuit typically indicates the inducer motor is not creating enough vacuum, often due to a clogged vent pipe, a cracked pressure switch hose, or a blocked drainage trap in condensing furnaces. If the signal remains open despite proper vacuum, the internal diaphragm or contacts may have failed.
Is the 12W49 compatible with 80% and 90%+ efficiency furnaces?
Yes, this switch is used across multiple Lennox platforms, but it is vital to match the 1.35" W.C. actuation point found on your existing part’s label. Installing a switch with the wrong pressure rating can lead to hazardous operation or frequent system lockouts.
How do I test the Lennox 12W49 for failure?
Technicians should use a manometer to verify the system is pulling at least 1.35" W.C. and a multimeter to check for continuity across the terminals once that pressure threshold is reached. Always ensure the furnace power is disconnected before removing the SPST leads.
Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.
Product Information
Product Information
Shipping & Returns
Shipping & Returns
Description
The Lennox 12W49 Pressure Switch (Model R20558702) is a critical OEM safety component engineered for precise combustion air monitoring in Lennox gas furnaces. This SPST pressure switch is factory-calibrated to actuate at 1.35" W.C., ensuring the inducer motor generates sufficient draft for safe venting before the ignition sequence begins. Designed for professional-grade reliability, it features a standardized 1/4" barb connection for secure pneumatic tubing attachment and a durable housing built to withstand the thermal cycling typical of modern HVAC environments.
As a low-fire pressure switch, the 12W49 provides essential feedback to the control board, preventing the operation of burners under hazardous conditions such as blocked flues or failing inducer assemblies. Whether you are performing a routine service or a critical repair, using this genuine Lennox HVAC part ensures exact fitment and maintains the factory-specified safety parameters of the equipment. This component is common in high-efficiency and modulating systems where accurate static pressure sensing is paramount for system performance.
Key Benefits
- OEM Precision: Guaranteed compatibility and performance as a direct Lennox furnace part replacement.
- Enhanced Safety: Monitors 1.35" water column pressure to verify proper exhaust venting and prevent carbon monoxide risks.
- Robust Construction: Built with SPST (Single Pole Single Throw) internal contacts designed for high-cycle industrial reliability.
- Universal Barb Fitting: Includes a 1/4-inch barb connection for seamless integration with existing pressure switch hoses.
- System Stability: Specifically engineered to reduce nuisance trips while maintaining strict adherence to combustion safety protocols.
Common Questions
What causes a Lennox pressure switch to stay open?
An open circuit typically indicates the inducer motor is not creating enough vacuum, often due to a clogged vent pipe, a cracked pressure switch hose, or a blocked drainage trap in condensing furnaces. If the signal remains open despite proper vacuum, the internal diaphragm or contacts may have failed.
Is the 12W49 compatible with 80% and 90%+ efficiency furnaces?
Yes, this switch is used across multiple Lennox platforms, but it is vital to match the 1.35" W.C. actuation point found on your existing part’s label. Installing a switch with the wrong pressure rating can lead to hazardous operation or frequent system lockouts.
How do I test the Lennox 12W49 for failure?
Technicians should use a manometer to verify the system is pulling at least 1.35" W.C. and a multimeter to check for continuity across the terminals once that pressure threshold is reached. Always ensure the furnace power is disconnected before removing the SPST leads.
Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.
