Viessmann Vitodens 333 Service Instructions Manual page 100

Function description
Control functions
External demand
The "External demand" function is
connected via the external extension
input "aVD".
In coding address "34" you can select
the influence the signal "External
demand" should have on the con-
nected circulation pumps.
Venting program
During the venting program, the circu-
lation pump will be alternately
switched ON and OFF for 30 s respec-
tively over a period of 20 min.
For a certain period, the changeover
valve is alternately set towards heat-
ing and DHW heating.
Filling program
In the delivered condition, the chan-
geover valve is set to its central posi-
tion, enabling the system to be filled
completely. After starting the control
unit, the diverter valve no longer goes
into its central position.
Filling with the control unit switched ON
If the system is to be filled with the
control unit switched ON, the change-
over will be moved to its central posi-
tion via code "2F:2" and the pump will
be started.
100
(cont.)
In coding address "9b" you can select
the minimum set boiler water tem-
perature in case of external demand.
The burner is switched OFF during
the venting program.
The venting program is activated via
coding "2F:1". The program is auto-
matically disabled after 20 min, and
the coding address "2F" is set to "0".
Afterwards, the changeover valve can
be moved via coding address "2F:2"
into the central position. In this posi-
tion, the control unit can be switched
OFF, and the system can be filled
completely.
The burner shuts down if this function
is enabled via coding address "2F".
The program is automatically disabled
after 20 min, and the coding address
"2F" is set to "0".