Viessmann Vitodens 300 Service Instructions Manual page 103

Control functions
External blocking
The "External blocking" function is
connected via the external extension
input aVD.
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 "Ext. demand"
should have on the connected circula-
tion pumps.
Venting program
Note
Close the gas shut-off valve when
operating the venting program.
During the venting program, the circu-
lation pump will be alternately
switched ON and OFF for 30 seconds
respectively over a period of
20 minutes.
Filling program
Note
Close the gas shut-off valve when
operating the filling program.
(cont.)
In coding address 32 you can select
the influence the signal "Ext. block-
ing" should have on the connected cir-
culation pumps.
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 address 2F:1. The program is
automatically deactivated after
20 minutes, and the coding address is
set to 0.
Function description
103