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millvolt + 24v on same t-stat

John T_3
John T_3 Member Posts: 34
I currently have my 750mv boiler and my 24v AC running on the same t-stat (honyewell VisionPro) The steam boiler is on R and W, and the AC is an Rc and the other correct terminals. The jumper is removed form R and Rh. All is working.


Can I cun the 24v common from my AC to the t-stat to power it? Or will this not work since the R is hooked up to the millivolt. Any thoughts? It works fine on the batteries, but would rather power it from the 24volt if possible.



  • bill_71
    bill_71 Member Posts: 46

    the rc and c terminal are used to power the thermostat. what you want to do is just fine and how that thermostat was intended to be wired
  • John T_3
    John T_3 Member Posts: 34

    thank you bill!
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