Viessmann Vitodens 200 Service Instructions Manual page 92

Function description
Extensions for external connections . . .
External extension H2
The external extension is connected
to the boiler control unit via the KM
BUS. The following functions can be
controlled or processed simulta-
neously via the extension:
A Mains isolator (on site)
sK DHW circulation pump (only for
weather-compensated opera-
tion)
fÖ Power supply
92
(cont.)
aVD External blocking
(terminals 2 - 3)
External demand
(terminals 1 - 2)
External heating program
changeover (terminals 1 - 2)
(only for weather-compen-
sated operation)
The allocation of function
"External heating program
changeover" is set via coding
address "91".
aVG KM BUS