Can it be done? Honeywell --> Nest

[R_D_C]

Hi All,

I am looking to replace an old-school round Honeywell thermostat with a Nest thermostat that I got a promotional deal on through my gas & electric company.   This old mercury switch style thermostat has only two-wires and only controls heat (oil driven, baseboard radiant hot water).  The first problem is the connections at this thermostat only provide a black and white wire.  Without a c-wire, the thermostat always balks with power errors, and the batteries quickly drain. 

Can a device such as the one linked here Thermostats 24 Volt Transformer C Wire Power Adapter for Nest  be used to provide the thermostat the power it needs in the absence of a proper c-wire? and if so, between the thermostat itself, and the power adapter, what should all of the leads be connected to? 

Unfortunately, the example in the amazon link looks to be more suited to a NEST E or Learning NEST, given the only connections I have are:

      Y  -  G

      C  -  R

      W  -  *OB

Appreciate any/all guidance!

rod

[Markjosephp]

Hello R_D_C,

Thank you for taking the time to let us know about your inquiry about whether a 24-volt transformer would work with the Nest Thermostat.

Given the situation where there's no C terminal on your circuit board, installing a transformer might still work to provide additional power to the thermostat. To be sure, could you please share with us a photo of your thermostat's wiring?

Regards,

Mark

[Jenelyn_O]

Hi there,
 

Chiming in — I hope you get the answer you're looking for. Please provide the photo of your thermostat wiring for us to take a closer look at it and assist you further.
 

I appreciate your help, Mark.
 

Thanks,

Jenelyn

[Jenelyn_O]

Hello there,

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'll be locking this thread in 24 hours.

Best,
Jenelyn

[R_D_C]

Hi Jenelyn and Mark,

Apologies for the late reply, was on the road and only just getting the chance to provide the photos.  Please see attached.  Your guidance is greatly appreciated!

Rod

[zoeuvre]

Hello @R_D_C,

I wanted to stop by and see how I could help. Since we can't clearly tell what labels you have on your Honeywell thermostat, please provide us a photo of your furnace control board where the other end of the thermostat wires are connected including their labels. I'll look forward to your response.

Thanks for the help here, Jenelyn and Mark. 

Best, 

Zoe

[R_D_C]

Hi Zoe,

Hi Zoe,

Hope this captures enough?  There are a few of these "junction" near the boiler, each labeled for the zone they control. The one in photo was labeled for the room/thermostat in question, and has the black and white wires that would seem to be the other end of what's connected at thermostat.

A slightly different angle showing some of the other connections and components:

Thanks!

Rod

[zoeuvre]

Hi there,

Thanks for getting back to us. I see that your control panel has the non-standard labels of T, T, 5, and 6 which means that your system is proprietary. 

Proprietary systems aren’t compatible with Google Nest Thermostats. However, some proprietary systems can be rewired by a pro installer to be compatible.

Let us know if that helps.

Thanks, 

Zoe. 

[Jenelyn_O]

Hi folks,

Chiming in — I hope you get the answer you're looking for. If you still have questions or concerns, please let us know.

I appreciate your help, Zoe.

Best,

Jenelyn

[Jenelyn_O]

Hello there,

We haven't heard from you in a while so we'll be locking this thread if there is no update within 24 hours. If you need assistance or want to discuss topics, feel free to start a new thread.

Thanks,

Jenelyn