Viessmann VITOTRONIC 300 GW2 Installation And Service Instructions Manual page 11

Heating system types for modulating boilers
Possible applications
Heating systems with distributor
arranged close to the boiler. The boiler
water flow is required to be reduced.
Please note:
This circuit diagram represents a
recommendation only. It is the
responsibility of the customer and/or
the 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
Vitotrol remote control
Flue gas temperature sensor
Coding Change required
system type
00: 1 If no system circuit A1 is connected, set
coding "00: 3", "00: 4", "00: 7" or "00: 8"
(see page 114)
02: 1 Set coding "02: 2" for operation with
modulating burner
03: 0 Set coding "03: 1" for oil-fired operation
(re-setting is not possible)
0C: 0 Set coding "0C: 1" for continuous return
temperature control
4A: 0
4b: 0
When the return temperature falls
below the required minimum value,
the temperature sensor T2 switches
on the shunt pump. If, as a result,
the required minimum return
temperature is not reached, the
return valve is proportionally closed
via the temperature sensor T1 and
the minimum return temperature is
assured.
The shunt pump must be sized so that
bypassed water accounts for approx.
30% of the total flow rate of the
boiler.
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Heating system types
(continued)
Automatic change
The system type is recognized automatically
when the sensors are connected
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Connection of the temperature sensor T1 at
plug aJA;
Coding "4A: 1" is set automatically
Connection of the temperature sensor T2 at
plug aJB;
Coding "4b: 1" is set automatically
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