Add thermostat and sensor wiring

Let's then add a thermostat, and sensor wiring.

Do the following:

Select Layout tab > Devices group > Heaters menu > Thermostat.
If necessary, turn the symbol by pressing F8.
Indicate the insertion point.
Draw a cable from the thermostat to the floor heating.
Select Layout tab > Devices group > Heaters menu > Sensor and wiring.
If necessary, turn the symbol by pressing F8.
Indicate the insertion point.
Accept the angle by right-clicking.
Select the start point for the sensor wire.
Indicate the next point. Using ortho helps inserting the wire.

Tip: If ortho is not on, you can activate it with Shift. Ortho will then be on for as long as Shift is pressed down. This also works vice versa, i.e. when ortho is on, you can temporarily turn it off with Shift.
Indicate the last point of the wire to the thermostat.