cancel
Showing results for 
Search instead for 
Did you mean: 

Wiring Configuration

Dwardo89
Community Member

The top picture is my older thermostat and the second picture is my attempt at installing my nest thermostat.

During set up it is saying that my W and Y are not connected and I cannot for the life of me find any info online about a set up where both the w and y use the white wire like my older thermostat does. 

Hoping someone can point me in the right direction.
5B343618-0125-4ACF-9825-A587816E0773.jpeg

image.jpg

9 REPLIES 9

CoolingWizard
Community Member

The device that the W and Y are coming out of is a special interface used by the old thermostat. It uses a single wire (white) to activate W for heat and Y for cooling. You will need a HVAC technician that is also a NestPro to make some changes.  You will need a No C-Wire adapter and the HVAC technician will need to rewire the HVAC system to use the white wire for Heat and the Black wire for Y cooling. Then the No-C Wire adapter will then bring C to the thermostat. 

NestPro and HVAC company owner

So theoretically, would running a new 5 conductor thermostat wire also do the trick?

Patrick_Caezza
Gold Product Expert
Gold Product Expert

That little adapter with the Y and W on it is not compatible with any Nest Thermostat.

If you look in the furnace/air handler I'm sure you will find another adapter connected to the white wire and the system.

It looks to be similar to the Add-A-Wire device that you can use to create a C wire. YOu can replace it with the Nest Power Connector which does the same thing but for Nest.

So theoretically, would running a new 5 conductor thermostat wire also do the trick?

Yes, replacing the existing cable with a 5-wire cable will eliminate the need for the Power Connector

MelbaDT
Community Specialist
Community Specialist

Hey folks, 

 

Thanks for taking care of this, Patrick_Caezza and CoolingWizard. 

 

Dwardo89, I hope you've got the answer you're looking for. Let us know if you have further questions in mind. 

 

Best, 

Melba

MelbaDT
Community Specialist
Community Specialist

Hey Dwardo89, 

 

Checking back in should you have more questions about this. Let us know by replying to this thread. 

 

Best, 

Melba

MelbaDT
Community Specialist
Community Specialist

Hi, 

 

We haven't heard from you in a while so we'll be locking this thread if there is no update within the day. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community.
 

Best, 

Melba

CoolingWizard
Community Member

If you can run a new thermostat wire between the thermostat location and the HVAC air handler it would help.  If  considering that the special splitter was used, I doubt it will be easy.  You need to have a good understanding of how the system works. Here is a bit of a primer.  The R wire brings 24 Volts AC to the thermostat. The G terminal controls the Blower Fan. The W terminal is used to call for a heat and the Y terminal is used to call for Cooling. If there is a heat pump outside, it will use a O/B wire. Lastly, the C terminal is for the Common or return path of the 24VAC. The thermostat connects R to G to turn in the blower fan, R to Y to turn on the AC compressor and the R to W to initiate Heating.  Now if you have a heat pump, the R will be connected or the O/B.  Some heat pumps default to cooling and some default to heating.  Simply put, R to O/B changes a heat pump form Heat to Cool or Cool to Heat. 

NestPro and HVAC company owner