Viessmann VITODENS 333-F WS3A Service Instructions Manual page 98

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 ON/OFF switch (on site)
sK DHW circulation pump (only for
weather-compensated opera-
tion)
fÖ Power supply
98
(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 the function
"External heating program
changeover" is set via coding
address "91".
aVG KM BUS