Viessmann VITODENS 300 WB3A, Service Instructions Manual

Page: 119 / 148

External blocking
The "External blocking" function is
connected via the external extension
input
aVD
.
In coding address 32 you can select
the influence the signal "Ext. block-
ing" should have on the connected cir-
culation pumps.
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.
In coding address 9b, you can select
the minimum set boiler water tem-
perature in case of external demand.
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.
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.
Filling program
Note
Close the gas shut-off valve when
operating the filling program.
Control functions
(cont.)
103
Function description
56
92
550
GB