How to wire Nest E with two wires directly connected with automatic gas valve and transformer?

[jitasi]

My old thermostat only has 2 wires, one white and one red/white. 

The wiring diagram provided by the furnace is as illustrated in the attached photo. 

https://photos.app.goo.gl/i1yX9V7XvoebvVsAA 

How should I connect the Nest Thermostat E with it?

[AxelD]

Hi jitasi,

Thanks for posting! I'm happy to help you with this wiring configuration assistance. I have a question about your thermostat:

• What are the tag letters on the thermostat for each wire? E.g. W and R.

In the case you have W and R or RC/RH. Here you have an image with the recommended wiring:

It's always recommended to have a C-WIRE or a Nest Power Connector because it will provide a stable power source for your Nest thermostat when your system can’t deliver enough consistent power to it. 

Regards,

Axel.

[jitasi]

I have W and R line.  I also have a nest power connector, but don’t know how to connect it

[AxelD]

Hi jitasi,

That sounds great! No worries, here you have a video tutorial that explains How to Install a Nest Power Connector for Your Nest Thermostat.

If you have more questions, let me know. 

Regards,

Axel.