Viessmann VITOTRONIC 300 GW2 Installation And Service Instructions Manual page 14

Heating system types
Heating system types for condensing boilers
System type 4 - Single-boiler system with Vitocrossal 300 with several heating circuits and one modulating supply
temperature heating circuit
A1
1
28
21
5
B
A Boiler with Vitotronic 300
B Domestic hot water tank
C Heating circuit with mixing valve
D Modulating supply temperature
heating circuit
or
E Underfloor heating circuit
F High limit thermostat (max. limit)
G Neutralizing unit
14
M2 M3
3
G A
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
sÖ A1 Heating circuit without mixing
valve (if installed)
sÖ M2 Heating circuit pump, mixing
valve circuit 2
sÖ M3 Heating circuit pump, mixing
valve circuit 3
(continued)
C
M2 M3
2 2
20 20
52 52
M3
2
D
F
20
52
Circulation pump for heating
sA
the DHW tank
sK DHW re-circulation pump
fÖ Power supply connection
120 VAC
Burner (1st stage)
fA
gS M2 Mixing valve motor, mixing
valve circuit 2
gS M3 Mixing valve motor, mixing
valve circuit 3
lÖ Burner (2nd stage/modulating)
aVD Connection of external
equipment (see page 38)
Connection of external
aVH
equipment (see page 39)
E