Viessmann VITOLIGNO 300-P Service Instructions Manual page 119

Control functions
Priority control
■ With priority control: (Code "A2:2"):
The set flow temperature will be adjus-
ted to 0 ºC during cylinder heating.
The mixer closes and the heating cir-
cuit pump is switched off.
■ Without priority control:
The heating circuit control unit contin-
ues to operate with the same set
value.
■ With modulating priority control in con-
junction with heating circuits 1 and 2:
The heating circuit pump remains
switched on. The set flow temperature
of the heating circuit will be reduced
until the set boiler water temperature
has been reached during cylinder
heating.
The set flow temperature is deter-
mined from the following parameters:
– Outside temperature
– Differential between the set and the
actual boiler water temperature
– Heating curve slope and level
– Setting of coding address "A2"
Frost protection
The DHW cylinder will be heated to
20 ºC if the DHW temperature falls below
5 ºC.
Auxiliary function for DHW heating
This function is activated by providing a
second set DHW temperature via coding
address "58" and activating the fourth
DHW phase for DHW heating.
(cont.)
Set DHW temperature
The set DHW temperature can be adjus-
ted between 10 and 60 °C.
The set range can be extended via cod-
ing address "56".
DHW circulation pump
The DHW circulation pump delivers hot
water to the draw-off points at adjustable
times.
Up to 4 time phases can be set at the
time switch.
Auxiliary circuits
DHW heating in conjunction with the
heating circuits can be disabled or ena-
bled by changing over the heating pro-
gram (see coding address "D5").
System with Vitosolic
Via coding address "67", a 3rd set DHW
temperature can be specified.
Reheating by the boiler will be sup-
pressed above this value. The DHW cyl-
inder is heated exclusively by the solar
thermal system.
Function description
119