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Help Please Wire for Boiler with the Power Connector πŸ’―

Community Member

Hello Helpers, 

Trying to get the Nest Thermostat installed with the POWER CONNECTOR. I got a boiler, so heat only - requiring: C, W and R at the boiler control panel. 

I can see W and R on my panel, but am confused about C, since there is C1 and C2. Also, can somebody confirm what's going on with the thermostat wire? The previous installer didn't use the thermostat connector T. 


The thermostat is connected already, but not enough power, so the wifi and battery fail. 

Thank you for your insight!

(Excuse the photos, after several attempts to correct them, they still view upside down)


20211202_144517 (1).jpg






Please be careful, there is high voltage in the boiler and for that kind of work it's always better to hire a pro unless you are proficient in electrical. C1 and C2 are not related to C wires.

Community Member

Sounding in on this, the setup is the same as mine, with 24v AC two extra wires in the box. Nest pro e setup type. Any answers?

OnTech installer in partnership with Google just came to install, and he wasn't familiar with this board. The Nest Learning Thermostat is compatible with the wires already installed given the lower voltage. So, without installing the C-connector in anyway. 

Seems with more information on this, I would have purchased the Learning version. That would be my recommendation. 

Given that during the summer he does say I may need to charge it(pulls off easy) because it loses battery when its not used. 



Community Member

@Dwooded what did you do, I have the same wiring. If C1 and C2 are not related to the"C" then what is?

C1, C2 are not related to the needed Constant wire. I got the more expensive Learning Thermostat, which doesn't need the C wire. In the process of returning the items(C-connector and Thermostat) back to Google. 


I only got the Rc and W1 wire connected, which were from the original(not Google) thermostat. 

Community Member

Going to have to run that c wire.

Community Member

Hi I am having the same issue. Just confirming that with the 3rd Gen Learning it worked and you didn’t need a power connnector?

Correct, yes. I did not need the Power Connector.