What To Do If; System Characteristics - Viessmann VITODENS 100-W Operating Instructions Manual

What to do if...

System characteristics

What to do if ...
... the heating system
does not come on
... the boiler does not
switch ON (or switches
ON infrequently)
... the burner does not
ignite, the fault symbol
"U" is displayed and
"Reset" flashes red
... the burner does not
ignite, display shows
fault symbol "U"
12
Cause
System switched off
System controls includ-
ing room thermostats
not calling for heat.
Rotary selector "tr" is
set to "9"
Fuse/MCB has blown/re-
sponded (either at the
fuse board or in the con-
trols)
No gas
Control fault
False start
Control fault
Solution
Switch on
Switch on system con-
trols to create demand
Set required heating
water temperature (see
page 9)
Contact your CORGI re-
gistered heating engineer
Contact your CORGI re-
gistered heating engineer
Read off the fault codes
in the display. Contact
your CORGI registered
heating engineer and re-
port the fault codes.
Press "Reset" button. If
this attempt to start is
also unsuccessful con-
tact your heating engi-
neer.
Read off the fault codes
in the display. Contact
the CORGI registered
heating engineer and re-
port fault codes.