I'm replacing an old thermostat with a slightly newer thermostat. It's connected to a heat pump and the old wiring (picture attached) was: White = W2 Yellow = Y Brown = O/B Red = R Green = G Blue = C

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The new thermostat doesn't have a C connection (see picture) so I'm not sure what to do with the wire. Note that the heat pump designations are on the outside edge of the thermostat.

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How do I wire the new thermostat? Any help would be greatly appreciated.

  • What model is your new thermostat? – ThreePhaseEel May 5 '18 at 0:39

Some of these thermostats do not require and do not give you a place for the common,blue wire. We call these thermostats power robbing thermostats. They have the ability to take enough power from the working wires to maintain their own functions without a common lead. This thermostat will work just fine without the common. Just cap it off and push it in behind the thermostat. The only drawback for this type of stat is that when you loose power to the house the stat won't work. Who cares! Nothing else works either.

  • Actually that is most likely a Honeywell Vision Pro thermostat operating off battery power. Still no need for the C wire, just need to change batteries about once a year. – user76730 May 5 '18 at 2:22

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