Viessmann Vitotwin 300-W Installation And Service Instructions For Contractors page 53

Terminal connections
Heating circuit with mixer
A
BSB 17
X4 1 2 X1 1 2 3 4
B
2 b
BSB
A Extension kit for heating circuit with
mixer
B Junction box
C Heating circuit 2 and 3 with mixer
(cont.)
Note
Never interchange wires.
2
C
Installation sequence
See separate installation instruc-
tions.
53