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Nest thermostat

Can a Nest E thermostat work on an Arm 3P control with priority...I know it says will not work with a high volt furnace. the control panel says 120 VAC. with no wire attached to the Common wire nor 24 V screws. I called the heating company that supplies the oil. They said it can be doen, but I need a 24 Volt transformer? I purchased a Nest C-wire adapter. When I tried installing the Thermostat, the furnace has a clicking sound within minutes of installation. The C-wire adapter looks complicated for me to attach. Please, any suggestions or help?


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    Read the recent dozens of posts on this site about what works and what doesn’t, in the real world, about Nest.

    There was an error rendering this rich post.

  • Jamie Hall
    Jamie Hall Member Posts: 23,543
    As a cirect answer, a Nest -- and indeed many thermostats -- is not meant for 120 volt AC operation. It can, however, be used to control a relay which, in turn, can control a 120 volt circuit. So yes, you need a 24 VA transformer, and a relay to control the furnace.

    I hope you did not try to connect the Nest to 120 volts... if you did, it's gone.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    HVACNUT Member Posts: 5,870
    Check the transformer in the Argo relay. Depending on the current load, you might be able to connect there. I wouldn't do more than one.
    A separate transformer and isolation relay would be preferred. 
    I have no idea what a Nest C wire adapter is and I don't wanna know. Because there's a better way. 

  • JakeCK
    JakeCK Member Posts: 1,401
    I hope you did not try to connect the Nest to 120 volts... if you did, it's gone.

    Sorry, couldn't resist.
  • jcaction
    jcaction Member Posts: 2
    i did try it....and i took it out....still works. Should I still call a Nest pro professional to look at it?