Help finding common and open wires for nest thermostat install

[Aizu]

Hi guys, I wonder if someone can help me.

I tried to install the Google nest e thermostat which Google swears can be self installed lol

I'm stuck trying to figure out the common wire, and open wire etc.

And also can i confirm the connection between 1 and 3 on the electrical diagram is the switch?

The nest app says :

"If there’s more than one line connected to your switch, the common wire is the shorter one with fewer objects in its path"

If there’s more than one line connected to your switch, the normally open wire is the shorter one with fewer objects in its path.

Am I right in concluding, based on the circuit diagram that
1) is the common wire
3) is the normally open wire

4) will be blocked



Images are attached

Many thanks in advance.

 

[Aizu]

Image 2

 

[ianmcd]

1 & 3 to
Com & NO on nestE either way round
4 isolated and tucked away

 

[Aizu]

1 & 3 to
Com & NO on nestE either way round
4 isolated and tucked away

Thanks very much buddy.