One of the 8 available circuits can be associated with DHW. It is customary to associate the circuit 8 as it is less likely to have been previously used for heating and/or cooling circuits:
PHOTO TBD
If a circuit is associated at the moment the DHW subsystem is activated, the circuit will also result active in Heating and will call the enabled sources (see SOURCES SETTING IN THE CIRCUIT PAGE).
If no circuit is associated, the current DHW set point is directly passed to the generators in the Opentherm page (DHW OPENTHERM):
PHOTO TBD
The choice of not associating a circuit is made, for example, when there is an instantaneous boiler when there is only one Opentherm generator than can manage DHW production by itself.