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Tn2 vs Tn4

JL_2 Member Posts: 17
Does anyone know the difference between Tn2 402 and Tn4 422? Or just the Tn2 and Tn4 in general?


  • SWEI
    SWEI Member Posts: 7,356

    TN4 is an older bus, but supports both controller to controller interconnection as well as controller to thermostat.  It requires 4 wires.

    TN2 is new, and (so far) is only used for controller to thermostat connections.  It requires only 2 wires.  This can sometimes save a lot of work on retrofits.