Allied Air 14A51 2-stage Pressure Switch

Product Description

The ALLIED AIR 14A51 is a 2-stage pressure switch designed for gas furnace applications. It monitors flue gas pressure to verify that the inducer motor is operating correctly before allowing ignition to proceed. With a high-stage set point of 0.74 inches water column (W.C.) and a low-stage set point of 0.41 inches W.C., this switch provides two-stage protection that matches the operating demands of two-stage gas furnace systems. Licensed HVAC technicians install this switch as a safety control component during routine maintenance or diagnosis of pressure-related lockout conditions.

This pressure switch is used in residential two-stage gas furnace installations where the furnace control board requires separate pressure confirmation signals for low-fire and high-fire operation. The 14A51 carries a cross-reference to Lennox part number 104549-09, making it a recognized replacement option in service situations where that part number is called out on a wiring diagram or parts list.

Key Features

• Two-stage design with independent high-stage (0.74 inches W.C.) and low-stage (0.41 inches W.C.) set points
• Functions as a safety interlock to prevent ignition when inducer airflow is insufficient
• Cross-references to Lennox 104549-09 for service identification
• Suitable for residential two-stage gas furnace systems

Compatibility

Cross-references to Lennox part number 104549-09. Designed as an OEM-style replacement for two-stage residential gas furnace pressure switch applications where that part number is specified.

Installation Notes

A licensed HVAC technician should perform pressure switch replacement. Power down the furnace and disconnect electrical supply before beginning work. Verify inducer operation and check flue and drain tubing for blockages or cracks before installing the new switch, as these conditions are a common root cause of pressure switch failures. Follow local mechanical codes and the furnace manufacturer's service instructions throughout the replacement procedure.

Technical Specifications

• Switch Type: 2-Stage Pressure Switch
• Set Point High Stage: 0.74 inches W.C.
• Set Point Low Stage: 0.41 inches W.C.

Standard Information

• Brand: ALLIED AIR
• Manufacturer Part Number: 14A51