Nest Thermostat advice

[JFPower8228]

Hello @CoolingWizard , may I seek your input please,  

 I intend to replace existing Honeywell thermostat (battery operated currently).   My wires are: G, Y, W,P

Per research, I can use the G wire as a C wire if we don't need the fan only option.   Is this an advisable path to proceed or does nest auto configure this.  The goal is to not use batteries or have to charge anything.  Just need the heat and cooling option but if there is a way to preserve fan only, would like to know.  Will current setup work?  I prefer not to install c wire adaptor 

 

[Patrick_Caezza]

@JFPower8228 

Using the G wire hack is not recommended.

The best option is to install the Nest Power Connector which is the correct way to solve the C wire issue.

[CoolingWizard]

@JFPower8228 ,

The G wire is needed when you are in Air Conditioner (cool) mode. Unlike a gas furnace, the air conditioner requires the thermostat to control the blower fan. 

When you remove your old thermostat, look for an unused wire that might be wrapped around the thermostat cable. If there is one, you can use it as your C wire.  if it is not there you will have to use a Google power adapter.

AC Cooling Wizard