wiring and system compatibility

[chassbarnes]

I have a summer home with a new boiler system and bought a Nest Thermostat to monitor the temperature in the house while we are not there. The current thermostat is the old round dial format. The wire present are red and white only. Is the nest thermostat ( not learning or E ) compatible with this wiring setup. There is no C wire. I would like to know before I open the package in case I need to return it. Thanks, Charlie

[CoolingWizard]

@chassbarnes ,

since you only have a heating system, the only two wires your nest thermostat will require will be the R and the W. 

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AC Cooling Wizard 

[Patrick_Caezza]

@chassbarnes 

A two-wire heat-only system will not work with the Google Nest Thermostat (2020) without a C wire or the Nest Power Connector installed.

[Terry7]

how do we hook up nest power connector with only 2 wires in furnace at transformer ?

[CoolingWizard]

@Terry7 ,

The Nest Power Adapter is designed to work with a 2 wire system.  R, W, C from the furnace are connected to the power and the R and W from the thermostat is connected to the other side of the power adapter.  

AC Cooling Wizard 

[CoolingWizard]

@Patrick_Caezza,

If the Nest Learning Thermostat Gen 3 is fully charged via USB when it is initially installed it will work until a Nest Power Adapter is installed. 

AC Cooling Wizard

[Terry7]

there is only 2 wires at transformer inside furnace ,no motherboard ,furnace built in 70 z 

[CoolingWizard]

@Terry7 , the Common side of the transformer is always connected to equipment ground.  The thermostat our wire will be connected to the line side of the transformer the other wire will be common. 

AC Cooling Wizard

[Patrick_Caezza]

@CoolingWizard 

The OP says they have the Google Nest Thermostat (2020) and not the learning thermostat so my statement is correct.

[CoolingWizard]

@Patrick_Caezza ,

A 2020 Nest Thermostat uses AA batteries and can still use R and C.  Furthermore, a 2-wire furnace can be properly operated by any Nest Thermostat. Since you Patrick you are not educated and experienced as a Mechanical Engineer or even an experienced HVAC service technician, you lack the full understanding of the HVAC control system.  Your knowledge and experience is simply a cursory level of experience.  

AC Cooling Wizard

[Patrick_Caezza]

@CoolingWizard 

Dude get over yourself.

You have no idea what my background and experience is.

Nest's thermostat compatibility chart clearly states that a C wire or a Nest Power Connector is required.

[CoolingWizard]

Well, @Patrick_Caezza , please do us all a favor and tell us about your CV.  I as well as the community would love to learn about your worldly skills and education in the HVAC industry.

AC Cooling Wizard, a HVAC/R professional