Allied Air 14T66 Combustion Air Pressure Switch 2-stage

Product Description

The ALLIED AIR 14T66 is a two-stage combustion air pressure switch kit used in gas furnace applications to verify adequate airflow through the heat exchanger before and during burner operation. It features a high set point of 1.00 inches water column (WC) and a low set point of 0.25 inches WC, allowing the furnace control board to confirm proper inducer operation at both low-fire and high-fire stages. Licensed HVAC technicians install this switch as part of routine furnace maintenance or component-level diagnostics on two-stage gas heating systems.

This pressure switch is designed for two-stage residential gas furnaces where the inducer motor operates at two distinct speeds. It functions as a safety interlock, preventing ignition or shutting down the burner if negative pressure in the flue or combustion air pathway falls outside acceptable limits. This part is also referenced under Lennox part number 104937-01, making it relevant for service work on Lennox-platform equipment as well as ALLIED AIR branded units.

Key Features

• Two-stage design with high set point of 1.00 inches WC and low set point of 0.25 inches WC
• Functions as a safety interlock to confirm inducer airflow before allowing ignition
• Cross-referenced to Lennox 104937-01 for broad serviceability
• Kit format includes switch and associated hardware for direct replacement

Compatibility

Referenced as a replacement for Lennox 104937-01. Designed for use in two-stage residential gas furnaces requiring a dual set point combustion air pressure switch.

Installation Notes

Installation should be performed by a licensed HVAC technician. Shut off electrical power and close the gas supply before servicing any furnace components. Pressure switch tubing connections should be inspected for cracks or blockages during replacement, as damaged tubing is a common cause of switch failure. Follow local codes and manufacturer wiring diagrams when reconnecting electrical leads to the control board.

Technical Specifications

• Switch Type: Two-Stage Combustion Air Pressure Switch
• Set Point High: 1.00 inches WC
• Set Point Low: 0.25 inches WC

Standard Information

• Brand: ALLIED AIR
• Manufacturer Part Number: 14T66