wiring compatiblity with old Thermostat

[EdLai]

Here is my old thermostat and wiring, it only controls the gas heating boiler.   How do I connect these wires to a Nest Learning Thermostat? 

[EdwardT]

Hi EdLai,

Thanks for reaching out. You can wire your Nest Thermostat by connecting the white wire to W1 and the black wire to RH. Nest thermostats are designed to use very little power, and in many cases they can use your system’s heating or cooling wires to get enough consistent power. But sometimes, you may need to connect a common wire (C wire) or power accessory, like the Nest Power Connector, to make your system compatible.

Thanks,

Edward

[EdwardT]

Hi EdLai,

It's me again. I wanted to check back in to see if you have other questions and concerns. Feel free to let me know if you do. 

Thanks,

Edward

[EdwardT]

Hi EdLai,

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.

Thanks,

Edward