I have a hot water boiler and separate AC system and bought a wifi smart honeywell thermostat to get a C wire- installed a 24 volt transformer that has two wires if one goes to the C where should the second wire land?

  • I'd suggest checking the wiring diagram and instructions that came with the thermostat. If your asking for help understanding those diagrams and instructions at the very minimum you need to give us the exact model number and/or a link to the online manual. Does your thermostat support this configuration with a second transformer? It may or may not. – Tyson Nov 20 '16 at 16:37
  • The Thermostat is a Honeywell 9580WF, – Marianne DiGiaro Nov 20 '16 at 17:09
  • Does the thermostat control both heating and cooling? – Tester101 Nov 20 '16 at 22:24

I just installed a Honeywell Lyric on my hot water boiler system. I did not purchase a separate transformer, but connected to an existing transformer. One wire goes to the C and the other goes to Rc.

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