Viessmann Vitotronic 200 KW2 Installation And Service Instructions Manual page 20

Installation
Burner connection
Two−stage/modulating burner extension
The function extension is supplied with the boiler.
Max. power consumption
H Two−stage:
1 (0.5) A
H Modulating: 0.1 (0.05) A
Observe coding addresses 02, 10 to 13, 15 to 18, 1A, 26 and 29 (see overview).
A
C
A To control unit
B To burner
C Junction box with relays
K1 and K2
20
(cont.)
B
Terminal codes
T6, T7, T8 Control chain Burner
stage 2 or modulation
controller (for two−stage
operation via two−point
controller; for modulating
mode via three−point
controller)
T6 From the burner
T7 Mod. burner closed
T8 Mod. burner open/
stage 2 ON
B
Signal pass direction:
Control unit → burner
Y
Signal pass direction:
Burner → control unit
Colour coding to DIN IEC 60 757
BK black
BN brown
BU blue