is the wiring compatible with Google Nest Learning Thermostat?

[PDNYC3]

[PDNYC3]

the bottom one is B

[CoolingWizard · Accepted solution]

From this picture, you look like you have a Heat Pump. There is no wire on the G terminal, which is odd, and there is a Black Wire on the RH terminal.  The Red Wire on the RC is your power incoming from the indoor air handler unless you have an all in one package unit outside.  The black wire on the RH is typically for a separate heating system such as a hot water boiler.  The Yellow wire on the Y terminal is for Cooling and the White wire typically is for Heat.  The Orange wire on the O terminal is for initializing the Heat Pump reversing valve.  If your system was a 100 percent heat pump system, you would have R, Y, O, G, and perhaps C. The Green wire you say is on the B terminal. The B is typically COMMON. Normally the G terminal is used to call for Blower Fan. When you switch the FAN switch from Auto to ON, the G send s a signal to the system to turn on the indoor blower fan.  The RH, and W tells me you have a secondary heating system in addition to the Heat Pump.   Is you AC system a split system or a packaged system?

Ken, the AC Cooling Wizard 

[PDNYC3]

yes its split.  You are right.

I guess it makes me think ill need an electrician

[Ryan_G]

Hey PDNYC3,

I just wanted to follow up and see if you're still in need of help. Please let us know as we would be happy to answer any questions you may have. 

Best regards,
Ryan
 

[Ryan_G]

Hey there,

Thanks for being here in the Google Nest Community. 

I'd like to bump in here and make sure that you’ve seen our response.
Please let us know if you have any other questions or concerns as I will be locking this thread in 24 hours.

Have a great day.

Best regards,
Ryan
 

[CoolingWizard]

Very few electricians understand HVAC control systems and thermostats, do not waste your money. 
The W terminal is probably being used to initialize emergency heat, The Rh (black wire) must be being used to give power to the Rh. and is more than likely connected to the control transformer with the Red wire.  Is the green wire connected to B at the bottom?

Do you have a Volt Ohm Meter? Check the AC voltage between Rc(red wire) and B ( green wire) and Rh (black wire) and B (green wire). If the green is indeed the COMMON, you will see approximately 24 Volts AC.  

If you want to just pay someone to come and figure this out and install a Nest thermostat, make sure they are an HVAC Company/Technician that are Google Nest registered. 

Ken, The AC Cooling Wizard

[Ryan_G]

Hey folks,

I just wanted to follow up and see if you're still in need of help. Please let us know as we would be happy to answer any questions you may have. 

Thanks for helping us here, CoolingWizard.

Best regards,
Ryan