Wattio THERMIC Manual Del Usuario página 53

SECOND, PHYSICAL INSTALLATION:
You can place the master THERMIC, where you will control the temperature at
home and the slave must be connected to the boiler. Both will replace the old
thermostat installation.
The THERMIC installation to the boiler must follow the next indications:
For a two wire installation, one of the cables will go on the position 3 and the
other cable on the position 1 or 2, according to the boiler type (normally open or
close).
The installation may have 3 or 4 cables, coming from the boiler. In this case:

Insulate the neutral cables

Insulate the ground cables

Insulate the cables that feed the relay, as the THERMIC works with
batteries
53