Viessmann Vitodens 333 Service Instructions Manual page 98

Function description
Extensions for external connections
External extension H2 (accessories)
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
fÖ
Power supply
98
(cont.)
aVD
&
External blocking
(terminals 2 - 3)
&
External demand
(terminals 1 - 2)
&
External heating program
changeover (terminal 1 - 2)
The allocation of function
"External heating program
changeover" is set via coding
address "91".
aVG KM BUS