Wiring Help - 2 wire systems

[Mrpmartin]

Hello

My systems is wired as follows:

We have hot water heated baseboards, and the plumber told me the thermostat needs to operate in reverse of normal zone valve operation. Meaning instead of opening the circuit to call for heat, the thermostat should close the circuit to activate the zone valve and stop the flow of hot water.

From what I can tell the Nest Learning Thermostat is compatible - how would it be wired properly based on this setup? @CoolingWizard 

[AxelD]

Hi Mrpmartin,

Thanks for posting! Here you have a reference image about how it should be wired: 

Please take note that it is recommended to have a C WIRE or Nest Power connector because it provides power directly to the thermostat. 

Regards,

Axel. 

[Mrpmartin]

@AxelD - Thank you for the response!

I've been getting a bit of conflicting information as to whether or not the Nest Learning Thermostat is compatible with a reverse zone valve. I messaged Google directly and one person said it was compatible, then a second said it wasn't, and now you're saying this is the correct wiring. So the Nest Learning Thermostat is for sure compatible with a reverse zone valve for hot water baseboard heating?

Is there anything else I would need to do to ensure the system functions properly?

I imagine I'm setting this up as Natural Gas and Radiant heat option? There is no cooling system, only heat. 

[AxelD]

Hi Mrpmartin,

Sure, I understand it can be confusing. I checked the compatibility using the Compatibility Checker tool and according to it, your system is compatible. The most important part to check the compatibility is the wiring and yours only has 2 wires. You could give it a try and just in case it doesn't work with your system, you can return it. 

Regards,

Axel.

[Mrpmartin]

Sure thanks. I've used the compatibility checker as well. I guess I don't want to worry about damaging the system if it is wired improperly. I'll keep looking to confirm what works with a reverse zone valve. Thanks.