topic Another R RC jumper question in Nest Thermostats

Another R RC jumper question

Alex_B9 — Mon, 29 Apr 2024 13:41:50 GMT

I am trying to install the 2nd gen Nest. The original thermostat has 2 RED wires in R terminal, which is jumped to RC one.
What should I do? Put both wires in RC in Nest? Or one (which is which - they look the same) in RC and another one in the RH??
I would add a picture, but I don't see the upload option here.

Re: Another R RC jumper question

David_K — Mon, 29 Apr 2024 14:08:58 GMT

Nest Thermostats don't use jumper wires. Don't connect more than 1 wire to a terminal in Nest Thermostat as that may damage it and/or your system.

Learn about thermostat jumper wires - Google Nest Help

An R wire can go into a Nest Learning Thermostat's Rc or Rh connector. When entering your wires into the app, don't select that you have an RC wire. It will tell you where to connect the R wire in Nest Thermostat.

Re: Another R RC jumper question

Alex_B9 — Mon, 29 Apr 2024 14:48:37 GMT

Thank you for a quick reply. The problem is that I have TWO RED wires coming together in the jumped R /RC terminal.
Should I put one in Rc and another in the Rh Nest terminals and see what happens?

Re: Another R RC jumper question

David_K — Tue, 30 Apr 2024 14:01:28 GMT

Ah I see what you mean, there is 2 wires into R, as well as a jumper from R to RC.

What do you see at the other end on the system board?

Re: Another R RC jumper question

Alex_B9 — Tue, 30 Apr 2024 14:22:06 GMT

Sorry, what do you mean by "other end"? At the heat exchanger unit?

One guess I have is the service person took out the Baxi boiler controller unit (which was apparently only needed for the initial boiler setup), shorted the wires (that unit has 2 wires), and stuffed them in the thermostat. My instinct tells me that they should go to the Rc in the Nest together, but I could be wrong.

Re: Another R RC jumper question

David_K — Wed, 01 May 2024 15:27:47 GMT

Yeah, if you followed those wires from the thermostat do they actually connect to anything?

Re: Another R RC jumper question

Alex_B9 — Wed, 01 May 2024 15:48:32 GMT

That's a good question. Since both the heater and AC work, they should. I can't really follow them, but I can try disconnecting one and see what will happen.