Viessmann VITODENS 200-W Service Instructions Manual page 96

Function description
Control functions
External blocking
The "External blocking" function is con-
nected via external extension input
"aVD".
External demand
The "External demand" function is con-
nected via external extension input
"aVD".
In coding address "34" you can select the
influence the "Ext. demand" signal
should have on the connected circulation
pumps.
Venting program
During the venting program, the circula-
tion pump will be alternately switched
ON and OFF for 30 s respectively over a
period of 20 min.
For a certain period, the diverter valve is
alternately set towards heating and
DHW heating. The burner is switched
OFF during the venting program.
Fill program
In the delivered condition, the diverter
valve is set to its central position, ena-
bling the system to be filled completely.
After switching ON the control unit, the
diverter valve no longer goes into its cen-
tral position.
Afterwards, the diverter valve can be
moved via code "2F:2" into the central
position. In this position, the control unit
can be switched OFF, and the system
can be filled completely.
96
(cont.)
In coding address "32" you can select the
influence the "Ext. blocking" signal
should have on the connected circulation
pumps.
The minimum set boiler water tempera-
ture in case of external demand is selec-
ted in coding address "9b".
The venting program is activated via
code "2F:1". The program is automati-
cally disabled after 20 min, and coding
address "2F" is set to "0".
Filling with the control unit switched
ON
If the system is to be filled with the control
unit switched ON, the diverter valve will
be moved to its central position via code
"2F:2" and the pump will be started.
The burner shuts down if this function is
enabled via coding address "2F". The
program is automatically disabled after
20 min, and coding address "2F" is set to
"0".