I have an R and an RC wire. Why is my system not compatible?? I also have a W, G and Y wire.

[Par428]

I used the compatibility checker before I purchased and it said my system was compatible.  But when I started the installation the Google Home App said that I wasn’t compatible.   Why not?? I have a G, W, Y and R  and RC  wire. Anyone know what’s wrong??

[Houptee]

Do you know if there are 2 transformers in the system? One in the furnace would be the Rh heat + and if the AC system has its own transformer that would be the Rc +

Is there a separate wire on Rc and Rh or is it just a jumper wire?

[Par428]

Thanks for the reply!  The red wires are separate......one on R......one on RC.    I don't have anything labeled RH

[Houptee]

You put the R to the Rh (heat) and Rc to Rc (cooling) those are both + 24V AC so you must have a transformer in the AC unit and another in the heating unit.

You will need to add a C wire Common hopefully the cable to the thermostat has a spare wire preferably Blue that you connect to C on the Nest. Then go to the furnace and find the thermostat wire and connect the Blue to the C terminal.

Then go back the the app setup and tell it you have a C wire and see what the app tells you.

[punit]

i dont have the C or any other extra wire.  when i open the back i have 1 wire with Red and white  and other cable has 3 wires.   G , Y and White.  dont have the 6th wire to make common connection 

[WDomingos]

hi there , i only have 4 wires on my system G-green, Y-black , W-white and Rc- red but the new nest thermostat does not have Rc connecter , only have 6 - Y,C,W,G,R & OB , where should i plug the Rc wire ?

please help.

[Robeyinc]

I have 2 separate wires. 

[Robeyinc]

I have a Rc and a Rh from 2 different systems but my nest only has a R? Can I only hook up one system?

[Bijan1]

I'm having the same problem as OP, but I only have a jumper, not a separate wire, to Rc. Should I continue with Nest installation and not select "Rc" as one of the wires in the Google home app?

[DSisno]

Same problem here. I have jumper wire 

[Houptee]

If you have a jumper wire between Rh and Rc you no longer need the jumper for the Nest. Just connect to Rh only. Nest thermostat never needs any jumper wires it internally jumps power as needed as long as you tell it the correct type of system you have. 

[Matt8]

I have a similar problem with nest . I have R,W,C conductors in one wire and on second wire I have Rc, Y,G . RC have 24 volts and R also . It’s two transformers but when I connecting to the nest base showing me like my thermostat doesn’t charging and R wire is little grey . For 2 years works with no problem now after the plumbers repleace relay in boiler it’s not working . Please help me 

[Houptee]

Do you mean they just recently replaced the relay for the boiler and now the nest doesn't work or the nest is new also? Upload a picture of the boiler relay wires possibly they didn't connect the C back on the relay and only hooked up R and W.

[Lindacmollicone]

I have the same problem  can I hook up a nest thermostat with a R and RC wire.

[DSisno]

Yes, you’re able to. I got mine to work. 

[Suesilv]

How? Same issue

[Suesilv]

Can you share how?

[Lindacmollicone]

what did you connect your RC wire to? I just connected my R wire but don’t know what to do with my RC wire.

[3Faisal]

I have RH and RC wire in my old thermostat the new nest thermostat has only one provision for R, how should i connect Rh and Rc? 

[Houptee]

You need the Nest Learning Thermostat for it to work with dual transformer systems, you have the regular Nest.

Or if you are good with wiring things you can install a relay near the heating system to make the Nest work with dual transformer systems.

[Suesilv]

I was told by nest support just to connect Rh and leave RC hanging???

[SonnyTrish]

from what i understand the nest only uses the c for charging.....the r and rh are switched and the rc and y are switched by the nest independently ...doe it matter which c i use from heat or AC