Viessmann Vitoladens 300-W Service Instructions For Contractors page 80

Function description
Control unit
(cont.)
The internal extension is factory-fitted
into the control unit casing. The following
functions are connected to the relay out-
puts:
sÖ Internal circulation pump
aXA Oil preheater
Extensions for external connections (accessories)
External extension H1
The external extension is connected to
the boiler control unit via the KM BUS.
The following functions can be controlled
or processed simultaneously via the
extension:
A ON/OFF switch (on site)
sÖ Heating circuit pump for the heat-
ing circuit without mixer
80
sA Circulation pump for cylinder heat-
ing
sK DHW circulation pump (only for
weather-compensated operation)
fÖ Power supply
gÖ Central fault message