Viessmann FB2B Installation And Service Instructions Manual page 137

Control functions
External demand
Input DE1
Input DE2
Input DE3
The effect on the internal circulation
pump is selected with code 3F.
The effect on the relevant heating circuit
pump is selected with code d7.
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 the fill function into the central
position (see "Filling the heating sys-
tem"). In this position, the control unit can
be switched OFF, and the system can be
filled completely.
Screed drying function
The screed function enables screeds to
be dried. For this, always observe the
details specified by the screed manufac-
turer.
(cont.)
The minimum set boiler water tempera-
ture in case of external demand is selec-
ted in coding address "9b".
Activate venting program: See "Venting
the heating system".
Filling with the control unit switched
ON
If the system is to be filled with the control
unit switched ON, the diverter valve is
moved in the fill program to its central
position and the pump starts.
When the function is enabled, the burner
shuts down. The program is automati-
cally disabled after 20 min.
Function description
Code
3A:2
3b:2
3C:2
137