How can I tell if my thermostat is high or low voltage to install a Nest Thermostat?

3 Answers

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  • 5 months ago

    If the wires are pliable and spaghetti thin then low voltage, if wires are stiff, three times larger in diameter, and using yellow or red wire nuts, high voltage, or 120v, line voltage, not high voltage.

  • Anonymous
    5 months ago

    In your other posy the picture is for the fan motor etc... The tstat is low voltage 18volts AC.

    Seems this is too complicated for you to do. Sounds like you need a HVAC tech or electrician.

    Hooking up the incorrect wires can do more damage than good. hooking up incorrectly you can damage the unit or the tstat. And that is not covered by warranty.

  • 5 months ago

    Doesn't matter. Many thermostats can be used on both

    What matters is the heating/cooling appliance.

    • JoKyoNim
      Lv 7
      5 months agoReport

      Not true. The only tstats that are 120volt is for electric heaters. Using 120volts to a low voltage tstat which many are will burn it up.

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