Viessmann VITODENS 343-F WS4A Installation And Service Instructions Manual page 101

Repairs
(cont.)
Boiler water temperature sensor, checking the cylinder tem-
perature sensor or the flow temperature sensor for a low loss
header
1. Boiler water temperature sensor:
Pull the leads from boiler water
temperature sensor A and check
the resistance.
Cylinder temperature sensor: Pull
plug % from the cable harness at
the control unit and check the resis-
tance.
Flow temperature sensor: Pull plug
"X3" from the control unit and check
the resistance across terminals
"X3.4" and "X3.5" (see page 99).
Troubleshooting
101