Viessmann VITODENS 333 Service Instructions Manual page 104

Function description
Control functions
The changeover of operating mode
remains active as long as the contact
remains closed, but no less than the
default duration selected with coding
address F2.
External blocking
The function External blocking is con-
nected via input aVD of the external
extension.
External demands
The function External demands is
connected via input aVD of the exter-
nal extension.
In coding address 34 you can select
the influence the signal Ext. demands
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.
104
(cont.)
In coding address 32 you can select
the influence the signal Ext. blocking
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.
The diverter valve is alternately
switched for a certain period towards
heating and DHW operation. The bur-
ner is switched OFF during the vent-
ing 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.