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Mitsubishi PAC-US444CN-1 and Nest

I have a 2 Mitsubishi AC Model SEZ-KD12NA4R1.TH Indoor Units that are ducted. These units are connected to a Mitsubishi MXZ-3C24NA2-U1 Outdoor Unit.

I have a 3 Mitsubishi AC Model SEZ-KD09NA4R1.TH Indoor Units that are ducted. These units are connected to a Mitsubishi MXZ-3C30NA2-U1 Outdoor Unit.

There is also a Mitsubishi PAC-US444CN-1 thermostat interface unit on each Indoor Unit that connects to a Nest Learning Thermostat.

I also have an Oil Heat, Forced Hot Water zoned system, the zones are controlled by the thermostats that also control the AC units.

How can I wire 5 Nest Learning thermostats so that I have optimum usage of the AC Systems?


  • ratio
    ratio Member Posts: 3,605
    If you have thermostats that control the heat & cooling together (as in not separate heating & cooling thermostats) that's about as good as you can get with the mini splits. They need the information provided by their native controls (wireless remote, wired or wireless stat, etc.) for modulating cooling operation.

    I did just hear about a home-automation system that can control mini splits by emulating a remote control, presumably that would allow the mini split to do it's thing.

  • Ironman
    Ironman Member Posts: 7,350
    The Nest is the worst possible thermostat that you could use on a modulating unit. It fights the logic of the mini split.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.