[blazer2020]

Well, my old thermostat has four wires, connected as follows:

Blue connected to C
Red connected to R
Yellow connected to 1
White connected to 2

Trying to determine how to connect to my new Nest.

Any thoughts?

 

[yuri]

What type of furnace do you have.

Post the brand name and model #.

Post the brand name and model # of the thermostat.

I suspect you have what is called a Communicating thermostat/which is like a computer data line.

R and C are the power and 1 and 2 the data.

You cannot swap a Nest in there and must use the brand name ( ie: Trane or Lennox ) tstat as the data is proprietary.

Some furnaces are backwards compatible but then you lose all the communicating features and have to configure the main circuit board which is messy and complicated and not always possible.

You would then need a fifth wire for the Nest if you have AC.

 

[blazer2020]

Thanks for the response.
This is at my son's house, so I will need to get the info from him.

I do know that their current thermostat is not just a basic model, it does display the outside temperature.

 

[roughneck]

The Nest is a very poor choice for a thermostat. Lots of bizarre problems and issues. I’ve personally seen some even cause damage to the equipment. Some have stuck on and the customer had woken up to a house in the 90s with the heat still running.
Nest markets the device as revolutionary but it’s far from it.
Honeywell and Ecobee make a superior product.

 

[yuri]

Thanks for the response.
This is at my son's house, so I will need to get the info from him.

I do know that their current thermostat is not just a basic model, it does display the outside temperature.

If it displays the outdoor temp then it is a Communicating type tstat.

Could be a Honeywell IAQ/ Indoor Air Quality system with a interface and outdoor sensor.

Point is you cannot replace it with anything by plug and play. If it is working then I would leave it alone.