Wiring for dual fuel system with eight wires. What do I do with the S1 and S2 wires?

[doc9983]

I have a dual fuel system. Current thermostat has 8 wires, Two of the wires are S1 and S2. Nest doesn't use these wires. Do I simply tape these. I have seen some diagrams that show the pink wire going in Y2 and the black wire going to the *. 

[Patrick_Caezza]

The S1 and S2 wires are from an external temperature sensor, and none of the Nest use it. Just tape them off.

Please post a picture of your original thermostat's wiring, and I will try to provide a wiring list.

[doc9983]

Current Wiring

[Patrick_Caezza]

Give this a try.

White - E to W2/AUX (jumper to AUX not needed)

Black - S1 - not used

White - S2 - not used

Red - RC to Rc (jumper to RH not needed)

Orange - O/B to OB

Yellow - Y to Y1

Gren - G to G

Blue - C to C

[doc9983]

Thanks for your help. I have seen several suggested configurations. Most agree with yours with one exception. The white is showing going to W1. Could this be because I have dual fuel and not auxiliary heat? 

[Patrick_Caezza]

You have a heat pump system and the yellow (Y) wire is what changes it between heating and cooling.

The white wire is for AUX heating and that is done on the W2/AUX terminal. You can use the W1 if you want, but the correct wiring is on the W2/AUX and why it is labeled as AUX

[doc9983]

Thank you for all your help.

[doc9983]

Nest says dual fuel setup should be done by a trained professional. Is there a guide available to take me through the setup?

[MelbaDT]

Hey folks, 

Appreciate your responses, Patrick_Caezza. 

doc9983, I'm afraid we can't provide a guide for this type of system as this is best done by a professional. Please get in touch with an HVAC technician or a local pro. They'll be the best one to talk about this. 

Best, 

Melba

[MelbaDT]

Hey doc9983, 

Checking back in should you still have some questions here. 

Best, 

Melba

[MelbaDT]

Hi, 

I haven't heard from you in a while so I'll be locking this thread if there is no update within the day. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community.

Best, 

Melba

[doc9983 · Accepted solution]

I was able to do the install myself with a little guidance from YouTube. The nest is up and running perfectly.  I love it. So glad I made this choice!! Thanks for all your help.

[MelbaDT]

Hey doc9983, 

Awesome ― glad to hear that you've managed to have it working. Give yourself a pat on the back for a job well done! 

Cheers, 

Melba

[MelbaDT]

Hi, 

I haven't heard from you in a while so I'll be locking this thread if there is no update within the day. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community.

Best, 

Melba