What To Do If; System Characteristics - Viessmann VITODENS 111-W Operating Instructions Manual

System characteristics

What to do if...

... the heating system will not
start
... the burner is not started or
starts intermittently
... the burner fails to start;
fault message "U" is dis-
played
... the burner shuts down
even if the rooms have not
reached their required tem-
perature
... the rooms have not
reached the required tem-
perature, even though the
burner is operational
... DHW temperature is too
low
Cause
No mains voltage
Rotary selector
"tr" is on "0"
Fuse/MCB in the
power distribution
board (domestic
mains fuse) or in
control unit has
blown/responded
No gas available
Control unit fault
False start
Water shortage
Fault in the ventila-
tion air supply or flue
system
Heating water tem-
perature or required
room temperature is
set too low
Air in the heating
system
DHW priority
Circulation pump
faulty
DHW temperature is
set too low or rotary
selector "tw" is on
"0"
What to do if...
Remedy
Switch on the ON/OFF switch
Setting the desired heating wa-
ter temperature (see page 11)
Notify your local heating con-
tractor
Open the gas shut-off valve and
if necessary check with your
gas supply utility
Check the fault code on the dis-
play. Notify your local heating
contractor and state the fault
code.
Reset burner fault (see
page 14) – if this attempt to
start also fails, notify your heat-
ing contractor
Notify your local heating con-
tractor.
Notify your local heating con-
tractor
Raise the heating water temper-
ature with rotary selector
"tr" (see page 11) or raise re-
quired room temperature (see
room temperature control unit
operating instructions)
Bleed radiators
Wait until the DHW cylinder has
been heated up
Notify your local heating con-
tractor
Set the desired DHW tempera-
ture
13