Is my thermostat compatible with Google Nest ?

[hgon23]

Here is the photo of my current wiring

This forum does not allow uploading photos ... 

[CoolingWizard]

@hgon23 ,

Your thermostat appears to only have two wires attached.  A green conductor is attached to the C terminal and and a white conductor attached to the R terminal.  This does nothing but power the thermostat itself.  It controls not equipment. lastly once you validate your email you will then be able to post pictures here.  

AC Cooling Wizard 

[hgon23]

Rc and R appears to be connected as well

[hgon23]

@Coop 

Are you suggesting that my current HoneyWell thermostat does nothing ?

The furnance and Heat pump does appear to be controlled by the thermostat; they start operating when the temperature drops below the set threshold and stop when the temperature reaches the set value.

[CoolingWizard]

@hgon23 

Your system might be using a RedLink interface and remotely controlling your HVAC equipment.  If this indeed the the setup, it will not be compatible with a Nest.

AC Cooling Wizard

AC Cooling Wizard 

[hgon23]

Looks like it has a Honeywell EIM

[hgon23]

So I guess I have to "bypass" it

[CoolingWizard]

@hgon23 , if you want to go to a more traditional system control, you would have to have a seven conductor thermostat cable installed between your thermostat location and the equipment. This may prove difficult and that’s why the contractor probably use the Honeywell RedLink system. This uses a high power Bluetooth technology.  This eliminates the needs for installing a new thermostat cable in order to utilize more advanced HVAC equipment.  

AC Cooling Wizard

[hgon23]

@CoolingWizard 

Roughly how much does it cost to get a HVAC perfessional to install the Google Nest thermostat for me ? I live in Bellevue WA area.

[CoolingWizard]

First of all, you would need them to install a new thermostat cable between the thermostat location and the indoor air handler/furnace.  I recommend a 10 conductor, 18 gage,  thermostat cable.  This will be the most expensive part of the project. Once the new thermostat cable is installed you can proceed with the installation of the Nest Thermostat.

The HVAC 10 conductor Thermostat cable typically contains:

Red, White, Yellow, Green, Orange, Black, Blue, Gray, Brown, and violet colored wires. We install the cable to the thermostat with Red on R or Rc, White on W/W1, Yellow on Y/Y1, Orange on O/B, Blue on C. 
No thermostat in the world knows the color of the wire. The key is what color a terminal at the thermostat you put the same on the air handler.  So red on R makes sense. 

Do you think you could install a new cable in your home? 

AC Cooling Wizard

[hgon23]

>> Do you think you could install a new cable in your home? 

What if I don't mind installing the Nest thermostat on the same spot of the EIM. Do I still need to install a new cable ?

[CoolingWizard]

@hgon23 , if you do not wish to install a new thermostat cable.  You could take the approach to install the Nest thermostat in the basement however, you would need to also purchase a Nest Remote Temperature sensor to be placed upstairs.  Otherwise the basement location of the Nest thermostat becomes the location of the temperature sensors.  

The ideal situation would be to put in a new thermostat cable between the thermostat location and the EIM furnace location.  

AC Cooling Wizard

[CoolingWizard]

@hgon23 , The EIM is the RedLink Equipment Interface Module.  This attaches to the Air Handler/Furnace like a thermost normally would. The RedLink compatible thermostat communicates with the EIM using high power Bluetooth.  

AC Cooling Wizard