Modine 5H0794410009 Pressure Switch 30067439-890 This establishes the initial water

This establishes the initial water seal required to combat static pressure and allow the furnace to drain under load

It ensures the damper returns to its default "normal" state (usually closed) during power interruptions

SPNO Configuration: Reliable Single Pole Normally Open design ensures the system fails-safe if pressure is lost or the inducer fails

opening on pressure fall to prevent evaporator freeze-ups or compressor cavitation

Modine 5H0794410009 Pressure Switch 30067439-890 This establishes the initial waterThe Modine 5H0794410009 Pressure Switch is the official OEM replacement part for legacy part number 5H79441 9. Specifically calibrated to a 0. 80" WC set point, this SPST (Single Pole Single Throw) air pressure switch is a critical safety interlock for Modine unit heaters, including the HD100, HD125, and PTS200 series. Its primary function is to verify that the inducer motor is creating sufficient negative pressure to safely vent combustion gases