Heating only - 2 wires - Nest setup not working

[Darbel]

I am hoping to swap out thermostat with Nest (non-learning) that I got free from utility provider. This thermostat only controls heat from a steam boiler to cast iron radiators. I have a five-wire strand to the thermostat with only the red and white wires connected to it. The boiler control board has three wires: H (appears red or brown) N (white) and B (green). The white and green from this control board are spliced to the white wire from the thermostat strand with a wire nut. Which would be the C wire and to which wire from the thermostat’s 5-wire strand do I connect it to?

[zoeuvre]

Hi Darbel, 

Thanks for posting here in the Community forum and for showing interest in our Nest Thermostats. Are you located in North America or Europe? For clear identification, send us a photo of the current wiring configuration of your thermostat and control board so we can take a closer look. You may also use our Compatibility Checker to determine if a Nest Thermostat is compatible with your system.

I'll look forward to your response. 

Best,

Zoe

[Darbel]

I am located in the United States. I don't see the option to add a photo and receive an error when trying to copy-clip an image stating" You do not have permission to upload images."  The furnace control board for the thermostat has four locations for wire connections and they are labeled, T, X, T and X.

[zoeuvre]

Hi Darbel, 

Thanks for getting back to us. Your control panel has the non-standard labels of T, X, T and X 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 you have any other questions.

Best,

Zoe