Wiring for nest thermostat

[Dh4]

I have wires for heat, fan, power, and 24V. What is the 24me? I have nothing for cool.

[zoeuvre]

Hi Dh4, 

Thanks for posting here in the Community forum and for showing interest in our Nest Thermostats. Let me take a look at this for you. 

24 V is your system's common wire that is responsible for providing additional power to your thermostat. To help us get a better picture of your thermostat wires' compatibility with our Nest Thermostats, what is the make and model of your current thermostat and your HVAC system? And do you mind sharing a photo of how the thermostat wires are connected to your current thermostat?

I'll look forward to your response.

Best,

Zoe 

[zoeuvre]

Hi Dh4, 

Thanks for posting here in the Community forum and for showing interest in our Nest Thermostats. Let me take a look at this for you. 

24 V is your system's common wire that is responsible for providing additional power to your thermostat. To help us get a better picture of your thermostat wires' compatibility with our Nest Thermostats, what is the make and model of your current thermostat and your HVAC system? And do you mind sharing a photo of how the thermostat wires are connected to your current thermostat? You may also check out our Compatibility Checker tool to help you determine if a Nest Thermostat is compatible with your heating and cooling system.

I'll look forward to your response.

Best,

Zoe