Viessmann Vitotronic 300 Operating Instructions Manual page 28

Troubleshooting guide
Diagnosis and correction
Fault
Burner does not start; red fault indi
cator flashes on the control unit
(see page 5) and red fault lamp is lit
on the burner
The rooms are cold even though the
burner is operating
The room temperature is not high
enough with a low outdoor tem
perature
Cold during the day, but warm at g y,
night
"Fault" flashes in the display win
dow
"Without function" appears in the
display window of the control unit
28
(continued)
Cause
Faulty start of burner
Time incorrectly set
g
Heating program "w" or "9" is set
(corresponding button is lit)
Operation with domestic hot water
cylinder only:
Domestic hot water supply has
priority (w in display window)
On/off switch on the mixing valve
motor is turned to OFF
Heating curve setting incorrect
Control unit incorrectly pro
grammed or set
Time incorrectly set
Control unit incorrectly pro
grammed or set
Fault on heating system
The button pressed has no function,
e.g. B if no DHW cylinder is con
nected
Remedy
Make a new attempt to start by pres
sing the reset button on the front of
the burner hood with pressure jet
burners, on the front panel of the
boiler with atmospheric burners.
If the burner still fails to operate
after pressing the reset button,
check the points stated in the sec
tion headed "Starting up the heating
system" and then press the reset
button again.
If the burner still fails to switch on,
contact your heating contractor.
Set correct time (page 20)
Set heating program "rw"
(page 6)
Wait until the domestic hot water
cylinder has heated up (w is extin
guished in the display window)
Turn the on/off switch to
I ON
Check and, if necessary, correct the
heating curve setting (page 21)
Check and, if necessary, correct the
settings for the temperatures (page
8), the time program (page 12) and
the heating program (page 7)
Set correct time (page 20)
Check and, if necessary, correct the
settings for the temperatures (page
8), the time program (page 12) and
the heating program (page 7)
Make a note of the fault code and
inform your heating contractor
(page 26)