The load is the total amount watts from all the heating cables connected to the thermostat. It is normally set during the intial set up of the thermostat. It can be set as an automatic measurement, or entered manually. If the installation consist of expansion unit(s)/power module(s), enter the total load manually. If it has not been done, the initial set up needs to be redone by doing a "Factory Reset" within the "Installer settings" menu