2 wire boiler . The 2 wire are blue and white

[JDottawa]

I see lots of discussion of how to connect R/W

But i have Blue/W only. The red one is not connected and may be dead.

Any ideas. Thanks!!!

[JDottawa]

https://i.imgur.com/kDAkvBI.jpg 

[Houptee]

What terminals are available on the system end? Post a pic of wires at your system. 

Looks like white is being used as power aka R usually that is a red wire.

Blue is being used as W usually a white wire.

[JDottawa]

Thank you!!

Not sure where to take a pic. Lots more wires at the boiler.

The blue wire seems to go into a plug like device (see circle bottom centre left. 

[Jhonleanmel]

Hey folks, 

Thanks again for helping here, @Patrick_Caezza and @Houptee. 
@JDottawa, I hope you've got the answer you're looking for. If you're still in need of any assistance, feel free to let us know. 

Best,
Mel

[Houptee]

Look for the (usually brown) cable with the colored wires coming from the thermostat and then take a picture of what they connect to. 

If this is a boiler for hot water heating system there might be a control box nearby the boiler where the thermostat wires connect. 

The picture you posted is internal wiring for the spark module that lights the gas burner so those are not thermostat wires.

[Jhonleanmel]

Hey everyone,

@Houptee, thanks for keeping tabs on this thread.

Best,

Mel

[aatienza]

Hey folks,

I just wanted to follow up to see if you still need our help. Please let us know as we would be happy to answer any questions you may have. 
 

Thanks,

Archie

[aatienza]

Hi there,

Just checking in to make sure that you've seen our responses. Please let me know if you have other questions or concerns as I will be locking this in 24 hours if I won't hear back from you again. Feel free to start a new thread and we'll be happy to help.
 

Thanks,

Archie

[Patrick_Caezza]

The color of the wires doesn't mean anything typically, as there is no set standard.

You would just connect the Blue (W) wire to the W terminal on the Nest.

The Google Nest Thermostat will not work with just the W and R wires connected. You are going to need to add a C wire.

I see that the thermostat cable appears to have extra wires in it.

Do you see the thermostat cable at the boiler side?

Are all of the wires connected or are some spare?

See if you can find the 24Vac trnasformer which looks simular to this. 

 Are any of the thermostat cable connected to it? If yes, which cable and what terminal.