Google Nest Community

alba23 · ‎12-10-2023

How to wire nest learning thermostat for 6 wire singe stage heating/cooling system with no heat pump

I have a Robertshaw digital programable Thermostat, 6 wires, 1 heat/1 cool stage. Wiring is as follows:

1. RH / RC are jumpered together

2. RH has no wire, Rh = 24 VAC Heating Transformer

3. Rc has Red wire, Rc = 24 VAC Cooling Transformer

4. W (White) = Heating Relay

5. Y (Yellow) = Cooling Relay

6. O (Orange) = Cool Active Reversing Valve

7. B (Blue) = Heat Active Reversing Valve

8. G (Green) = Fan Relay

How do I wire to Nest Learning Thermostat

zoeuvre · ‎12-14-2023

Hi alba23,

Thanks for posting here in the community forum and for showing interest in our Nest Thermostats. You have a single-stage heating and cooling system with a heat pump based on your current thermostat wiring configuration, as the O terminal represents the heat pump, which is your cool active reversing valve. With that being said, your thermostat wires are compatible with our Nest Learning Thermostat 3rd generation and Nest Thermostat E and should be wired to the Nest Learning Thermostat as shown:

With Nest Learning Thermostat 3rd generation:

With Nest Thermostat E:

Disregard the jumper wire, as that is not needed in Nest Thermostat. Also, here's a guide for the installation and setup of a Nest Learning Thermostat and a Nest Thermostat E.

Let us know how it goes.

Best,

Zoe

alba23 · ‎12-14-2023

Thanks Zoe,

Can you please explain why my blue wire (heat active reversing valve) goes to the C terminal (common wire) on my nest?

zoeuvre · ‎12-18-2023

Hi there,

I'm sorry for the delayed response. Wires labeled B typically should go into a Nest Thermostat's OB connector. But for some systems the wire in the thermostat's B connector is actually a common or C wire. Common wires should go in your Nest Thermostat's C connector. If the B wire is blue, it should most likely be connected to the C connector. Visit this identify a thermostat wire article for more.

Thanks,

Zoe