Viessmann WB2-44 - Page 33

Troubleshooting
33
Cause of fault Corrective action
Short circuit – WS/RS remote control unit Check WS/RS remote control unit (see page 44).
Open circuit – WS/RS remote control unit or wrong
coding
Check WS/RS remote control unit (see page 44).
Check proper system coding.
Internal BUS f ault
Verify connections X5.3 and X5.4 for mixing valve
(if applicable).
Check that circuit board VR20 is inserted properly and check
field su
p
p
lied connections (b
y
p
rocess of elimination if
Open circuit – internal BUS connection
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required).
Check coding of LGM 29 component part.
Replace circuit board VR20 or circuit board of burner control
unit LGM 29 (see page 61).
KM-BUS fault to Vitocom Check connection to Vitocom or Vitocom defective.
Short circuit/open circuit – BUS connection to extension
kit for heating circuit with mixing valve
Check connection of extension kit for heating circuit with
mixing valve (see page 25). Check coding for system
with a mixing valve. Mixing valve might be defective.
Set DIP switches to factory default setting. See symbols on
back of programming unit.
Sensor inputs are not read correctly. Check correct connection of sensors.
Check for damage on wiring harnesses.
Check whether circuit board VR20 is defective.
If required, replace circuit board VR20
*1
.
Data points are not stored; internal fault VR20. Replace circuit board VR20
*1
.
AD-converter of burner control unit defective;
internal fault LGM 29
Replace burner control unit LGM 29
*1
.
Differential air pressure sensor / open circuit Check wiring, replace sensor.
Differential air pressure sensor / short circuit Check wiring, replace sensor.
Internal fault or fault with internal data protection Reset burner control unit.
Fault in Dekamatik-HK heating circuit control unit
connected downstream
Check Dekamatik-HK heating circuit control unit connected
downstream and data transmission circuit. Check wiring con-
nections.
Error message to Vitocom communication unit Check Vitocom communication unit.
Error message extension kit for heating circuit with mixing
valve
Check coding for extension kit and the extension kit itself.
Check sensor of mixing valve.
Parameterization of burner control defective Replace circuit board of burner control unit LGM 29
*1
.
Emergency operation LGM 29 Check plug-in connection and circuit board VR20.
Replace circuit board VR20 if necessary.
Parameterization of burner control defective Replace circuit board of burner control unit LGM 29
*1
.
5285 961 v1.3