Viessmann VITODENS 200 Start-Up/Service Instructions page 35

Vitodens 200 WB2 Service
Correction
(continued)
Legend
A DHW tank temperature sensor
B Low-loss header temperature sensor
Transducer power supply
X14.3 . . . . . . . . . . . . . . . . Red
X14.4 . . . . . . . . . . . . . . . . Yellow
X14.5 . . . . . . . . . . . . . . . . Black
Between red and black: . . . . 24VDC
Between black and yellow:
at standby . . . . . . . . . . . . . 0.2 to 0.3VDC
at ignition . . . . . . . . . . . . . 0.7 to 1.0VDC
at low fire . . . . . . . . . . . . . 0.5 to 0.6 VDC
at high fire . . . . . . . . . . . . .3.5VDC
Check DHW tank temperature sensor or low-loss header
temperature sensor
1. Disconnect connector "X7" from the control unit.
2. Measure resistance of the tank temperature sensor
and compare with the curve.
3. If the value measured differs significantly, replace
the sensor.
4. Repeat above steps 1 - 3 for checking the low-loss
header temperature sensor.
Check and replace differential air pressure sensor
In case of fault messages regarding the differential air
pressure sensor, check that;
the sensor was installed correctly.
the electrical connections were made correctly.
the O-rings in the adaptor are correctly positioned.
the test nipples have been sealed with plugs.
If the error message persists, replace sensor.
To check O-rings:
1. Disconnect electrical plug-in connection 164 A.
2. Remove sensor B by pulling off in an upward direction.
3. Check that the two O-rings C are correctly located
in the mountings D of the adaptor.
4. Insert connection nipples of the sensor in the adaptor
of the gas combination valve and snap into place.
5. Reconnect the electrical plug-in connection on the
sensor.
Troubleshooting
35