Google Nest E 2 wire installation..

[HomerJay99]

Hi all,
I’m trying to install my Nest E as per the instructions for a 2 wire system there doesn’t seem to any useful labels on the existing thermostat that would allow me to connect to the correct terminals of the Nest E.
All I have are 2 wires (blue & brown) and a clipped earth that are connected to 2 terminals on the Honeywell that are marked A and B. (See pic)
Can anyone tell me what to connect here - I was hoping that the existing thermostat would be clearly marked but A and B is a bit vague!

 

[CBW]

Yes, A is live in and B is switched live out, which should be sleeved brown if mains voltage.

So Brown to Com and Blue to NO

 

[ianmcd]

But cut back those wires, shouldnt be any copper showing, your origional installation is very poor

 

[HomerJay99]

Thanks guys, all done and seems to be working. Now just have to sit back and collect all those sweet, sweet savings..hopefully.

 

[ericmark]

How does Nest e save money over any other on/off thermostat?

OK using OpenTherm maybe, but using on/off could just as easy be connected to the house alarm so once set heating switches off.

The whole idea is only to heat rooms when required, and to the temperature required. So we want a TRV programmable head in every room, if linked to the wall thermostat even better.

At around £50 per programmable TRV head with wireless link to wall thermostat, with 15 TRV's in this house, it gets a bit costly, so one has to decide how far to go, non linked TRV heads and price drops to £15 each, at least that is what I paid, and in theory the TRV does not need to be linked, all the wall thermostat does is stop boiler cycling in warm weather.

However it seems Nest has a mind of its own, for one reason or another I have had to turn off all the smart features, bit useless really.