Nest C wire issue

[LudoNYCParis]

I have the 3 wire (red, white and blue) for my Nest however, only one has 24V, the red cable.

The white cable is connected to W1.

Oddly enough if I connect that 24V red wire (supposedly the C wire?) to the C plug I get a wire report issue.

If I connect it to the RH it works correctly.

However, as the thermostat doesn't get power it only last a few hours.

In that configuration the remaining blue cable remains unconnected. The reason is that if I connect that blue cable to the C connector then the Thermostat does get power (!) even-though that wire doesn't carry any voltage. BUt the problem is that when the thermostat requires heat i.e. turns the boiler on, then power is intermittent. The boiler constantly gets turned on and off. A pretty loud clicking noise on the boiler can be heard.

I am in that situation were what looks like the C wire (with the 24V)  has to be plugged into the RH for everything to run correctly but then, as I previously wrote, the thermostat doesn't get power and only runs on battery for a few hours.

Does anyone has a suggestion?

[ByronP]

Hi LudoNYCParis,

Thank you for posting in the community. I'm sorry that you're experiencing troubles with your Nest Thermostat with the C wire that doesn't get enough power when you turn on the heating. I understand how confusing this must be. I'm here to help.

A C wire is dedicated to delivering constant power and stabilizing the flow of current into the Nest Thermostat.

For further assistance, I need to ask a few questions:

• What type of Nest thermostat do you have? ( Here is the reference on how to identify your Nest Thermostat)

• Did you use the compatibility checker to test your system?

• What did the compatibility checker direct you?

• Did you use the setup flow in the app and check compatibility?

Please keep me posted. I look forward to your response.

Regards,

Byron