Lennox 73W35 Pressure Switch
The Lennox 73W35 Pressure Switch is a critical safety and operational component designed for 2-stage gas furnaces. This OEM Lennox replacement part, also identified by part number 102737-09, monitors the pressure differential created by the combustion air inducer to ensure the system is venting correctly before ignition. For multi-stage heating, this dual-stage pressure switch features precise set points: a high-stage set point of 0.55" W.C. and a low-stage set point of 0.25" W.C.. These calibrated specs are vital for maintaining the efficiency of Lennox EL280 series units and other compatible 80% and 90% efficiency models. As an SPST-N.O. (Single Pole Single Throw, Normally Open) device rated for 24 VAC at 5 Amps resistive, it prevents hazardous operation by breaking the circuit if the flue becomes obstructed or the inducer fan fails to reach the required RPMs during either stage of the heating cycle.
Key Benefits- Precise 2-Stage Monitoring: Explicitly calibrated for 0.55" and 0.25" W.C. stages to ensure optimal performance across different firing rates.
- Exact OEM Fit: Drop-in replacement for Lennox 102737-09, eliminating the need for field adjustments or universal bracket modifications.
- Enhanced Combustion Safety: Automatically prevents furnace ignition if negative pressure is lost, protecting the heat exchanger from improper venting.
- Proven Reliability: Constructed to withstand the high-temperature environment of the furnace cabinet near the cold end header box.
How do I know if my Lennox furnace pressure switch is bad?
Technicians typically look for error codes indicating "pressure switch stuck open" or "stuck closed." If the inducer motor is running but the igniter doesn't glow, check for continuity across the 73W35 terminals while the motor is under load. Blown diaphragms or cracked plastic ports are common physical indicators of failure.
What is the difference between a high-fire and low-fire pressure switch?
In 2-stage HVAC systems, the low-fire switch (0.25" W.C.) monitors the initial startup and low-capacity run, while the high-fire switch (0.55" W.C.) proves sufficient airflow when the furnace ramps up to full capacity. The 73W35 is engineered to handle these specific differential requirements accurately.
Can I use a universal pressure switch instead of the 73W35?
While universal switches exist, Lennox 2-stage furnaces require exact set point accuracy to maintain the SureLight control board logic. Using a switch with the wrong "WC" rating can lead to intermittent short-cycling or ignition failure on the second stage.
This item is not eligible for free shipping.
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.
Lennox 73W35 Pressure Switch
The Lennox 73W35 Pressure Switch is a critical safety and operational component designed for 2-stage gas furnaces. This OEM Lennox replacement part, also identified by part number 102737-09, monitors the pressure differential created by the combustion air inducer to ensure the system is venting correctly before ignition. For multi-stage heating, this dual-stage pressure switch features precise set points: a high-stage set point of 0.55" W.C. and a low-stage set point of 0.25" W.C.. These calibrated specs are vital for maintaining the efficiency of Lennox EL280 series units and other compatible 80% and 90% efficiency models. As an SPST-N.O. (Single Pole Single Throw, Normally Open) device rated for 24 VAC at 5 Amps resistive, it prevents hazardous operation by breaking the circuit if the flue becomes obstructed or the inducer fan fails to reach the required RPMs during either stage of the heating cycle.
Key Benefits- Precise 2-Stage Monitoring: Explicitly calibrated for 0.55" and 0.25" W.C. stages to ensure optimal performance across different firing rates.
- Exact OEM Fit: Drop-in replacement for Lennox 102737-09, eliminating the need for field adjustments or universal bracket modifications.
- Enhanced Combustion Safety: Automatically prevents furnace ignition if negative pressure is lost, protecting the heat exchanger from improper venting.
- Proven Reliability: Constructed to withstand the high-temperature environment of the furnace cabinet near the cold end header box.
How do I know if my Lennox furnace pressure switch is bad?
Technicians typically look for error codes indicating "pressure switch stuck open" or "stuck closed." If the inducer motor is running but the igniter doesn't glow, check for continuity across the 73W35 terminals while the motor is under load. Blown diaphragms or cracked plastic ports are common physical indicators of failure.
What is the difference between a high-fire and low-fire pressure switch?
In 2-stage HVAC systems, the low-fire switch (0.25" W.C.) monitors the initial startup and low-capacity run, while the high-fire switch (0.55" W.C.) proves sufficient airflow when the furnace ramps up to full capacity. The 73W35 is engineered to handle these specific differential requirements accurately.
Can I use a universal pressure switch instead of the 73W35?
While universal switches exist, Lennox 2-stage furnaces require exact set point accuracy to maintain the SureLight control board logic. Using a switch with the wrong "WC" rating can lead to intermittent short-cycling or ignition failure on the second stage.
This item is not eligible for free shipping.
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.
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Description
The Lennox 73W35 Pressure Switch is a critical safety and operational component designed for 2-stage gas furnaces. This OEM Lennox replacement part, also identified by part number 102737-09, monitors the pressure differential created by the combustion air inducer to ensure the system is venting correctly before ignition. For multi-stage heating, this dual-stage pressure switch features precise set points: a high-stage set point of 0.55" W.C. and a low-stage set point of 0.25" W.C.. These calibrated specs are vital for maintaining the efficiency of Lennox EL280 series units and other compatible 80% and 90% efficiency models. As an SPST-N.O. (Single Pole Single Throw, Normally Open) device rated for 24 VAC at 5 Amps resistive, it prevents hazardous operation by breaking the circuit if the flue becomes obstructed or the inducer fan fails to reach the required RPMs during either stage of the heating cycle.
Key Benefits- Precise 2-Stage Monitoring: Explicitly calibrated for 0.55" and 0.25" W.C. stages to ensure optimal performance across different firing rates.
- Exact OEM Fit: Drop-in replacement for Lennox 102737-09, eliminating the need for field adjustments or universal bracket modifications.
- Enhanced Combustion Safety: Automatically prevents furnace ignition if negative pressure is lost, protecting the heat exchanger from improper venting.
- Proven Reliability: Constructed to withstand the high-temperature environment of the furnace cabinet near the cold end header box.
How do I know if my Lennox furnace pressure switch is bad?
Technicians typically look for error codes indicating "pressure switch stuck open" or "stuck closed." If the inducer motor is running but the igniter doesn't glow, check for continuity across the 73W35 terminals while the motor is under load. Blown diaphragms or cracked plastic ports are common physical indicators of failure.
What is the difference between a high-fire and low-fire pressure switch?
In 2-stage HVAC systems, the low-fire switch (0.25" W.C.) monitors the initial startup and low-capacity run, while the high-fire switch (0.55" W.C.) proves sufficient airflow when the furnace ramps up to full capacity. The 73W35 is engineered to handle these specific differential requirements accurately.
Can I use a universal pressure switch instead of the 73W35?
While universal switches exist, Lennox 2-stage furnaces require exact set point accuracy to maintain the SureLight control board logic. Using a switch with the wrong "WC" rating can lead to intermittent short-cycling or ignition failure on the second stage.
This item is not eligible for free shipping.
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.
