I have a heat pump system with 5 wires on the thermostat where the yellow and white are tied together (and this system has been working fine for 2+ years). Couple questions about this setup:

1) Why are the white and yellow wires tied together?

2) I'm trying to hook up a Nest (3rd gen). Its terminals only take 1 wire. Support wasn't much help and told me that my current setup is wrong and the white/yellow wires should not be tied. How do I switch to the Nest setup properly?

picture of old setup (which is working fine):

enter image description here

Thank you in advance for any help!

  • 1
    Check the other end at the furnace, give us the names of the terminals the wires are connected to. It sounds like standard color codes where not used. – Tyson Nov 25 '16 at 20:46
  • @Tyson Thanks for the reply. I'll have to hunt down the other end and get back to you with that info. – SudoKill Nov 25 '16 at 21:10

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