Viessmann Vitotronic 200 Installation And Service Instructions For Contractors page 116

Function description
DHW heating control (cylinder temperature control)
Brief description
The set boiler water temperature for DHW heating is
■
regulated to a constant value (cylinder temperature
control). It operates by starting and stopping the cir-
culation pump for cylinder heating.
The switching differential is
■ When the DHW cylinder is heated, a set boiler water
temperature is specified that is 20 K higher than the
set DHW temperature (adjustable at parameter "06"
in the "DHW" group).
Functions
Time program
An automatic program or an individual time program
may be selected for DHW heating and the DHW circu-
lation pump.
Compared with the heating circuit heat-up phase,
DHW heating starts 30 min earlier in automatic mode.
The individual time program enables up to 4 time pha-
ses per day to be set for DHW heating and the DHW
circulation pump.
All started DHW heating sequences are completed
irrespective of the time program.
In conjunction with parameter "7F" in the "Gen-
eral" group
Detached house
■
Parameter "7F:1":
Automatic mode
–
The heating times for heating circuit 1 are applied
to systems with 2 or 3 heating circuits.
– Individual time program
The time phases for DHW heating and the DHW
circulation pump have the same effect on all heat-
ing circuits.
■ Apartment building
Parameter "7F:0":
– Automatic mode
For systems with 2 or 3 heating circuits, the heat-
ing times for the respective heating circuit will be
applied.
Individual time program
–
The time phases for DHW heating and the DHW
circulation pump can be adjusted individually for
each heating circuit.
116
2.5 K.
±
Priority control
■ With priority control: (Parameter "02:2" in the "Heat-
ing circuit..." group):
The set flow temperature will be adjusted to 0 °C
during cylinder heating.
The mixer closes and the heating circuit pump is
switched off.
■ Without priority control:
The heating circuit control unit continues to operate
with the same set value.
With modulating priority control in conjunction with
■
heating circuits with mixer:
The heating circuit pump remains switched on. Dur-
ing cylinder heating the set flow temperature of the
heating circuit will be reduced until the set boiler
water temperature has been reached.
The set flow temperature is determined from the fol-
lowing parameters:
– Outside temperature
– Differential between the set and the actual boiler
water temperature
– Heating curve slope and level
Setting of parameter "02" in the "Heating cir-
–
cuit..." group
Frost protection
The DHW cylinder will be heated to 20 °C if the DHW
temperature falls below 5 °C.
Additional function for increased DHW heating
This function is activated by providing a 2nd set cylin-
der temperature in parameter "03" in the "DHW" group
and activating the 4th time phase in the DHW time pro-
gram for DHW heating.
Set DHW temperature
The set DHW temperature can be adjusted between
10 and 60 °C.
Parameter "01" in the "DHW" group enables the set
range to be extended to 95 °C.