Nest - C connector troubles

[Vmangino]

Hello,

I have a natural gas boiler. No AC. There is originally only a White and a Red wire. So per Google I need a c connector. So I purchased the c connector. 

Now this gets strange. So I took the red and white wire coming out of the boiler and went to a junction that was randomly in the basement and I spliced in the red and white to the c-connector and the thermostat is not working.

So trouble shooting I have done. Leaving connected as is, without c connector the thermostat works but with limited function. So reads the white and red and has provided heat no problem. Then I add the c connector and connect it to the thermostat. It reads the c wire and the red wire, but no longer reads the white wire and I have no idea why. This doesn't seem like it should be this difficult. 

Does anyone have suggestions?

[Houptee]

Can you pull a new 5 conductor thermostat cable from the Nest to the boiler? This is the best method to get a C wire.

If not then for the power connector you need to put it at the boiler and it has to have a C terminal at the boiler where the thermostat wires connect.

3 of the wires go directly to the boiler C R and W, and the other 2 wires go to R and W going directly to the Nest.

Some boilers have a separate relay box that the thermostat wires go to and the older ones like Honeywell do not have a C terminal available.

Take a pic of the boiler where the thermostat wires are connected so we can tell if there is a C terminal. 

Watch this video.

https://www.youtube.com/watch?v=xlx2Um6D1Z8&list=PLw9wSQ08iHfhObdjthN2eY4On8uiYu0Sr&index=2&t=14s&ab...

[Vmangino]

Thank for for your quick response. I have a third wire in the wall already but it is not connected to boiler. My guess is it was never hooked up when my boiler was changed to natural gas because it wasn't needed with the thermostat I have. I am not sure how too attach pictures to this reply.

[Houptee]

If you have that spare wire then that is the best solution use it for the C wire.

Boilers usually have a Taco or Honeywell control box where the tstat wires connect.

Do you have more than one zone, more than one tstat in the system?

[Vmangino]

My control box doesn't seem to have a label on it. By boiler is a burnham alpine by us boiler company. I see a boiler controls system labeled "sage 2". I also see all the terminals that the red and white wire are connected to. They are: heating tstat, heating tstat. Dhw temp switch (2). Outdoor sensor (2). Header sensor (2). Remote firing rate (2). External limit (2). 

I also have a transformer on the side of the boiler. I attempted to connect a c wire to that but it only turns on and off with the boiler it seems so it was not constant power.

I only have one zone.  I do not see anything labeled "C"

[Jake]

Hey there,

Thanks for the help Houptee.

I wanted to check in and see if you are still in need of any help. Please let me know, as I would be happy to assist, and answer any questions you may have.

Best regards,
Jake

[AbigailF]

Hi folks,

We’d like to check in again in case you have any further questions or concerns. Feel free to reply to this thread and we’ll help you out.

Thanks, 
Abi

[AbigailF]

Hello everyone,

I'm just checking in to make sure that you've seen our response. Please let us know if you have any other questions or concerns as I will be locking this in 24 hours.

Cheers,
Abi

[Houptee]

Call US Boiler and ask them where to connect the C wire for your smart thermostat to that Boiler model number. 

[Dobermann]

Hi Houptee, Could you please take a look at my thread:

HELP! Have Five Nest Thermostats & 5 Nest Power Co... - Google Nest Community

How do I wire in this setup?  Thanks in advance