Operating instructions

Troubleshooting guide
34
Diagnosis and correction (continued) Vitocontrol-S, VD2/CT3/CM2
Fault Cause Remedy
Heating circuit does not start up
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”
8
”
Switch on
Power supply disconnect switch, if
installed, is switched off
Switch on power supply disconnect
switch
Heating program ”9” is set (corre-
sponding button is illuminated)
Set ”rw” or “w“ heating program
(page 10)
Fuse in the domestic power circuit
or in the control unit has blown or
tripped
Inform heating contractor
Fault on control unit After consulting your heating con-
tractor, the boiler can be operated
temporarily with constant boiler
water temperature by turning the
override switch ”S” to ”h”; leave
cover open
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, check domestic
hot water temperature, 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
b
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r
s
a
r
e
o
p
e
r
a
t
i
n
g
Time incorrectly set Set correct time
T
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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
Control unit incorrectly programmed
or set
Check and, if necessary, correct the
settings for the temperatures, the
time program and the heating
program
5351 341 v1.2