Allied Air 14A47 2-stage Pressure Switch 0.55 0.35 Wc

Product Description

The ALLIED AIR 14A47 is a 2-stage pressure switch designed for use in gas furnace applications. It monitors negative pressure created by the inducer motor to confirm proper draft before allowing ignition to proceed. This switch features two set points: a high-stage set point of 0.55 inches water column (WC) and a low-stage set point of 0.35 inches WC, corresponding to the two firing stages of a two-stage furnace. Licensed HVAC technicians install and replace this component during maintenance, troubleshooting, or furnace commissioning. It is a safety-critical control that prevents furnace operation when adequate venting pressure is not established.

This pressure switch is suited for residential two-stage gas furnaces that require separate pressure monitoring for low-fire and high-fire operation. It replaces Lennox part number 104549-05 and is appropriate for forced-air heating systems using an induced-draft or power-vented configuration. Install scenarios typically involve switch replacement after a failed pressure switch diagnosis, inducer motor replacement, or control board servicing where the switch is found out of tolerance.

Key Features

• Two-stage operation with distinct high and low set points for accurate draft verification
• High-stage set point: 0.55 inches WC
• Low-stage set point: 0.35 inches WC
• Direct replacement for Lennox 104549-05
• Safety-critical function prevents ignition without confirmed inducer draft

Compatibility

Replaces Lennox part number 104549-05. Designed as an OEM-style replacement pressure switch for 2-stage residential gas furnaces requiring dual set-point draft monitoring.

Installation Notes

A licensed HVAC technician should install or replace this pressure switch. Disconnect power to the furnace at the disconnect switch or breaker and shut off the gas supply before beginning any service work. Verify the inducer motor and flue venting are clear of obstructions before replacing the switch, as a blockage can cause a new switch to fail the same way. Follow all applicable local mechanical codes and the furnace manufacturer service instructions when reinstalling hose connections and electrical terminals.

Technical Specifications

• Switch Type: 2-Stage Pressure Switch
• Set Point High: 0.55 inches WC
• Set Point Low: 0.35 inches WC

Standard Information

• Brand: ALLIED AIR
• Manufacturer Part Number: 14A47