Viessmann VITOTRONIC 300 GW2 Installation And Service Instructions Manual page 10

Heating system types
Heating system types for modulating boilers
System type 2 – Single-boiler system with shunt pump and return valve for raising the return temperature
in conjunction with
Vitorond 200, VD2
1
28
21
5
B
A Boiler with Vitotronic 300
B Domestic hot water tank
C Heating circuit with mixing valve
*1
On the Vitorond the boiler supply and return are at the rear of the boiler.
10
M2 M3 A1
17B
17A
3
plugs
! Outdoor temperature sensor
? M2 Supply temperature sensor,
mixing valve circuit 2
? M3 Supply temperature sensor,
mixing valve circuit 3
§ Boiler temperature sensor
DHW tank temperature sensor
%
aJA Temperature sensor T1
aJB Temperature sensor T2
sÖ M2 Heating circuit pump, mixing
valve circuit 2
sÖ M3 Heating circuit pump, mixing
valve circuit 3
sA Circulation pump for heating
the DHW tank
(continued)
M2
2
20
52
T2
T1
*1
A
sK
sL
fÖ
fA
gS A1 Mixing valve motor for raising
gS M2 Mixing valve motor, mixing
gS M3 Mixing valve motor, mixing
lÖ
aVD
aVH
C C
M3
2
20
52
DHW re-circulation pump
Shunt pump
Power supply connection,
120 VAC
Burner (1st stage)
the return temperature
valve circuit 2
valve circuit 3
Burner (2nd stage/modulating)
Connection of external
equipment (see page 38)
Connection of external
equipment (see page 39)