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Water radiant heat 2 wires R +W only

Community Member

I am trying to see is the nest thermostat or E (not learning) is compatible with my system. I have 5 zones so I need  thermostats. 

I have two wires attached to the thermostats. W and R only. These are low voltage.



Community Member

HVAC technician here... You can use the Nest E thermostat for each zone as it doesnt require a C terminal. Although it's a huge expense for a simple on/off radiant heat only system. You may go through batteries like crazy though without both a R and C terminal which powers the stat normally. 

Community Member

I was told by google phone support

Nest Thermostat learning will work with no batteries and no C adapter

Nest Thermostat E will also work with no C adapter and no batteries

Nest thermostat (new 2023 ) will need either batteries or adapter.


Do you disagree?


Community Member

In my experience the learning thermostat will not work. It may work but you will have intermittent issues with it connecting and sending the signals.


I would personally go with the nest E thermostat but try a learning stat if you want? I would do one stat for a week and see how it works on a zone but that's a big investment for that many zones... 

Community Specialist
Community Specialist

Hi folks,


Thanks for posting in the Google Nest Community forum. I'm sorry for the delay. If you only have two wires, you can either use the Nest Learning Thermostat or Nest Thermostat E. However, if you prefer to use the Nest Thermostat 2020 you might need to invest in C wire or Nest Power Connector. 


You can visit this support article for more information.


I appreciate the input, @kpaterniti.




Community Specialist
Community Specialist

Hello everyone,

Thanks for the on-point explanation @kpaterniti, and for your assistance, Jenelyn.

@HAP1, in addition to what was shared above, the Nest Thermostats are compatible with zoned system panels. But some zone relays don't provide enough power to the thermostat. In most cases, it needs the Nest Power Connector or a Common wire to deliver constant power.

Let us know if you have more questions.


Community Member

To answer you question about the cost: Fancy house that needs a more user friendly system. I flip homes and the thermostats are in need of an upgrade.