How to install a Google Nest thermostat

Hi guys,

I’m trying to replace a Salus+Honeywell thermostat with a Nest one. I have currently a Salus thermostat that I use to set up the mode and schedule the heat and then a Honeywell that I use to set up the temperature.

I bought a Google Nest thermostat 3rd generation. The installation should be fairly simple but I don’t understand how to connect the cables as they are labeled differently in the previous system. Also I’m not sure how to combine the functionalities of the two thermostats and where to position the heat link and where the thermostat.

Below some pictures.

Can someone help?


Hey Fabrizia,

First of all, if you have any doubts about wiring you should call an electrician, I’m not a qualified one, but I can tell you what I think is going on.

I can see you have a remote control that have power, Neutral (N) and Live (L), that’s 220v, plus, a relay inside the thermostat will send 220v as live down to CH4, that’s to signal the boiler to turn on.

I don’t understand what’s going on in the second picture, would be great if we can have more info? also, as a reference, a picture of the nest? mine it’s on the wall…