Viessmann Vitotronic 100 GC1 Series Operating Instructions And User's Information Manual page 13

Diagnosis and correction with single-boiler systems
Fault
Heating system does not start up
Burner does not switch on
The burner is operating, but no hot
water
(only on systems with domestic (only on systems with domestic
hot water tank) hot water tank)
Cause
Heating system switch "8" turned
to OFF on the control unit
Electrical isolator switch, if installed,
is switched off
Fuse in the domestic power circuit or
in the control unit has blown or
tripped
Heating program "9" is set (the
corresponding button is illuminated)
Vitoair draught stabilizer defective
(only on boilers with pressure jet
burner)
Failure of motor-controlled flue gas
damper (only on gas boilers with
atmospheric burner)
Fault on control unit
No fuel
Control unit incorrectly programmed
or set
DHW tank temperature sensor or
circulation pump for heating the
DHW tank defective
Troubleshooting guide
Remedy
Switch on
Switch on electrical isolator switch
Inform heating contractor
Set "rw" or "w" heating program
(page 6)
Inform heating contractor.
Change setting of Vitoair to
manual operation:
Press in rotary knob A on
motor and turn fully beyond
setting "4".
Inform heating contractor.
Change setting of motor-controlled
flue gas damper to manual operation:
Press in rotary knob A on motor and
turn fully beyond setting "4".
After consulting your heating
contractor, the boiler can be operated
temporarily with constant boiler
water temperature by turning the
emissions test switch "S" to "h";
leave cover open
Oil or LPG
Check fuel supply and re-order if
necessary.
Natural gas:
Open gas-shut off valve or contact
gas supply company if necessary.
Check domestic hot water
temperature and correct if
necessary (see page 10)
Inform heating contractor
A
A
13