York S1-024-35266-000 .45/.85″ SPNO Close On Fall Pressure Switch

Description

York S1-024-35266-000 SPNO Close On Fall Pressure Switch

The York S1-024-35266-000 is an OEM replacement pressure switch engineered for use in York furnaces and HVAC systems. Configured as a Single Pole Normally Open (SPNO) switch with a “Close On Fall” action, this switch monitors negative pressure (draft) within the combustion air circuit and closes its contacts when pressure drops to the designated set point — providing a critical safety interlock that confirms proper inducer operation before allowing ignition to proceed.

Key Features

• OEM York replacement part — ensures precise fit and reliable performance
• SPNO (Single Pole Normally Open) configuration — contacts close on pressure fall
• Dual pressure set points: .45″ and .85″ W.C. (water column)
• Close On Fall action — switch closes when sensed pressure drops to set point, confirming adequate draft
• Designed for draft inducer pressure sensing in gas furnace applications
• Provides essential safety interlock to prevent ignition without confirmed airflow
• Direct OEM replacement for compatible York furnace models

How It Works

The pressure switch is connected to the draft inducer housing via a sensing hose. When the inducer motor runs and creates the required negative pressure, the switch contacts close, signaling the control board that safe combustion conditions exist. If the inducer fails or airflow is blocked, the pressure does not fall to the set point and the switch remains open — locking out ignition and protecting the system and occupants from unsafe operation.

Application

• York OEM gas furnace pressure switch replacement
• Draft inducer airflow verification
• Combustion safety interlock circuits
• Compatible with select York residential and light commercial furnace models

Specifications

• Part Number: S1-024-35266-000
• Switch Type: SPNO (Single Pole Normally Open)
• Action: Close On Fall
• Set Points: .45″ / .85″ W.C.
• Brand: York