Viessmann Vitoligno 300-P Service Instructions For Contractors page 104

Function description
Control functions
Functions
The flow temperature of heating circuits
1 and 2 is captured by the flow temper-
ature sensor.
Time program
The control unit time switch regulates in
accordance with the times programmed
in the "Heating and DHW" program
between "Central heating with standard
room temperature" and "Central heating
with reduced room temperature".
Every operating mode has its own set
level.
Outside temperature
A heating curve must be set up for
matching the control unit to the building
and the heating system (see page 31).
The heating curve characteristics deter-
mine the set boiler water temperature
subject to outside temperature. An aver-
age outside temperature is used for con-
trol purposes. This comprises the actual
and the adjusted outside temperature.
Room temperature
In conjunction with the remote control
and room temperature hook-up (coding
address "B0"):
Compared to the outside temperature,
the room temperature has a greater influ-
ence on the set boiler water temperature
(change via coding address "B2").
104
(cont.)
DHW temperature
■ With priority control:
The set flow temperature will be adjus-
ted to 0 °C whilst the cylinder is being
heated up.
The mixer closes and the heating cir-
cuit pump is switched OFF.
■ Without priority control:
The heating circuit pump continues 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 tempera-
ture of the heating circuits will be
reduced, for as long as the set boiler
water temperature has not been
reached during cylinder heating. This
is subject to the differential between
the set and the actual boiler water tem-
peratures, the outside temperature,
the heating curve slope and the setting
of coding address "A2".
Heating circuit pump logic (economy
mode)
The heating circuit pump is switched
OFF (set flow temperature set to 0 °C)
when the outside temperature exceeds
the value selected via coding address
"A5".