Viessmann VITOTRONIC 100 GC1 Installation And Service Instructions Manual page 32

Heating system types
Circuit Diagram 13
Possible applications
For heating circuits with temperature
differences ≥20 K.
The cascade and DHW tank control
must be activated by a building
automation system.
IMPORTANT
This circuit diagram represents a
recommendation only. It is the
responsibility of the customer and/or
heating contractor to check that this
recommendation is complete and fully
functional. Three-phase equipment
must be connected via additional
power contactors.
Available system accessories
Flue gas temperature sensor
Coding of Change required
system type
01: 1 Set coding "01: 3" for multi-boiler system
with external cascade control via switch
contacts
02: 1 Set coding "02: 2" for operation with
modulating burner
0C: 4 Only with Vitotronic 100 for the Vitocrossal
300:
Set coding "0C: 0"
Only with Vitotronic 100 for the Vitorond
300: Set coding "0C: 1" for continuous
return temperature control
0d: 2 Only with Vitotronic 100 for the Vitocrossal
300:
Set coding "0d: 0"
4A: 0
4d: 1 Only with Vitotronic 100 for the Vitocrossal
300:
Set coding "4d: 2" for boiler circuit pump at
plug sL
32
(continued)
The Vitocrossal 300 (lead boiler) and
the Vitorond lag boilers are operated
with modulating boiler water
temperature and load-dependent
sequential control by means of the
outdoor-reset logic control system.
Two-stage or modulating burners
can be controlled.
Through the control system which is
linked via the LON BUS, the boiler
supply temperature which is
established is higher than the
maximum heating circuit supply
temperature by an adjustable
difference. The heating system can
be operated in accordance with a
separate heating curve.
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The Vitocrossal 300 boilers have
two return connections. The heating
circuits with the higher return
temperature are connected to the
return connection at the top, those
with the lower temperatures to the
return connection at the bottom.
Please note:
At least 15 % of the
take-off from the rated output must
be connected to the return connection
at the bottom.
The T1 temperature sensor measures
the return temperature.
The return valve is activated via the
boiler control unit so as to ensure that
the return temperature does not fall
below the minimum value.
Automatic change
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Only with Vitotronic 100 for the Vitorond:
Connection of the Therm-Control temperature
sensor at plug aJA;
Coding is automatically changed to "4A: 1"