Viessmann GC1 - Page 32

Troubleshooting guide
32
Diagnosis and correction (continued) Vitotronic 300-K, MW1S
Fault Cause Remedy
Heating circuits does not start up
Power supply disconnect switch,
if installed, is switched off
Switch on power supply disconnect
switch
Heating program ”9” is set
(corresponding button is illuminated)
Set ”rw” or “w“ heating program
(page 6)
Fuse in the domestic power circuit
or in the control unit has blown or
tripped
Inform heating contractor
Burners are operating, but no hot
water (only on systems with DHW
tank)
Control unit incorrectly programmed
or set
Check time program for domestic
hot water heating (page 12 and
15), check domestic hot water
temperature (page 18), and correct
if necessary
DHW tank temperature sensor or
re-circulation pump for the DHW
tank is defective
Inform heating contractor
The rooms are cold even though the
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Time incorrectly set Set correct time (page 20)
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burners are operating
Heating program ”w” or ”9” is set
(corresponding button is illuminated)
Set heating program ”rw”
(page 6)
Operation with domestic hot water
tank only:
Domestic hot water supply has
priority (w in display window)
Wait until the domestic hot water
tank has heated up (w is turned off
in the display window)
On/off switch on the mixing valve
motor is turned to OFF
Turn the on/off switch to
I ON
The room temperature is not high
enough with a low outdoor tempera-
ture
Heating curve setting incorrect Check and, if necessary, correct the
heating curve setting (page 21)
Control unit incorrectly programmed
or set
Check and, if necessary, correct the
settings for the temperatures (page
8), the time program (page 12) and
the heating program (page 7)
5581 751 v1.1