Allied Air 80W51 2-stage Pressure Switch 0.55 in Wc

Product Description

The ALLIED AIR 80W51 is a 2-stage pressure switch designed for use in gas furnace draft inducer control circuits. It monitors flue gas pressure to verify proper venting before allowing burner ignition, acting as a safety interlock within the furnace control sequence. The switch features a high set point of 0.55 inches water column (W.C.) and a low set point of 0.35 inches W.C., providing two-stage pressure sensing for furnaces that operate at both low-fire and high-fire stages. Licensed HVAC technicians install and service this component as part of routine furnace repair and maintenance work.

This pressure switch is used in residential gas furnaces that employ 2-stage heating operation. It is installed in the draft inducer circuit to confirm adequate negative pressure before energizing the gas valve. The 80W51 is also referenced under Lennox part number 104549-05, making it a relevant replacement candidate for techs servicing equipment under that cross-reference. Typical applications include induced-draft and forced-draft furnace platforms where dual set-point pressure monitoring is required.

Key Features

• 2-stage operation with high set point at 0.55 inches W.C. and low set point at 0.35 inches W.C.
• Functions as a safety interlock, preventing ignition if proper draft pressure is not established
• Cross-referenced to Lennox part number 104549-05
• Designed for induced-draft and forced-draft residential gas furnace applications

Compatibility

Cross-referenced to Lennox part number 104549-05. Designed as an OEM-style replacement pressure switch for 2-stage residential gas furnaces requiring a high set point of 0.55 inches W.C. and a low set point of 0.35 inches W.C.

Installation Notes

Installation and replacement of furnace pressure switches should be performed by a licensed HVAC technician. Disconnect power to the furnace and shut off the gas supply before beginning any service work. Verify that the replacement switch set points match the furnace manufacturer specifications before installing. Inspect the pressure switch hose and port for cracks, blockages, or moisture that could cause nuisance trips after installation.

Technical Specifications

• Switch Type: 2-Stage Pressure Switch
• Set Point High: 0.55 inches W.C.
• Set Point Low: 0.35 inches W.C.

Standard Information

• Brand: ALLIED AIR
• Manufacturer Part Number: 80W51