Cylinder Temperature Control - Viessmann Vitoligno 300-C Installation And Service Instructions For Contractors

Control functions
(cont.)
The temperature limiter switches the heating circuit
pump off if the set value has been exceeded. The flow
temperature is only slowly reduced in this situation, i.e.
it may be several hours before the system restarts
automatically.
Lower control range limit
Electronic minimum temperature limit

Cylinder temperature control

Brief description
Cylinder temperature control is a constant tempera-
■
ture control. It operates by starting and stopping the
circulation pump for cylinder heating.
The switching differential is 10 K.
■ Central heating is switched off during cylinder heat-
ing. When cylinder priority control is active, see code
A2, heating system group.
Coding addresses that influence the cylinder tem-
■
perature control:
– 0C, 0D (DHW group)
– A2 (heating group)
For a description, see codes overview.
Functions
Time program
An automatic program or an individual time program
may be selected for DHW heating and the control of
the DHW circulation pump.
Via the time switch in the individual time program up to
4 time phases per day can be set to control DHW heat-
ing, and 4 time phases for the DHW circulation pump.
All cylinder heating sequences will be completed inde-
pendent of the time program.
Priority control
The priority control of the cylinder heating can be
adjusted individually for each heating circuit.
■ With priority control: (code 2 "A2:2", heating 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.
With priority control: (code 2 "A2:1", heating group):
■
The set flow temperature will be adjusted to 0 °C
during cylinder heating.
The mixer closes and the heating circuit pump is run-
ning.
Only possible when the heating circuit is wired on the
internal boiler PCB. When using an extension kit for
the heating circuit, the heating circuit pump is
switched off.
Setting range: 1 to 127 °C
Change via coding address "C5".
Only enabled during operation with standard room
temperature.
■ With reduced priority control: (code 2 "A2:3", heating
group)
The heating circuit pump remains switched on. Dur-
ing cylinder heating, the set flow temperature of the
heating circuit will be reduced to the set value of
reduced heating mode until the set flow 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
■ Without priority control: (code "A2:0", heating group)
The heating circuit control unit continues to operate
with the same set value.
Set DHW temperature
The set DHW temperature can be adjusted between
10 and 70 °C.
The set range can be extended via the menu.
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.
System with Vitosolic
A second set DHW temperature can be specified via
coding address "67".
Reheating by the boiler will be suppressed above this
value. The DHW cylinder is heated exclusively by the
solar thermal system.
Control sequence
The circulation pump for cylinder heating starts when
the differential between the buffer cylinder temperature
(top sensor) and the actual cylinder temperature
exceeds the setting (coding address "0C").
Function description
113