Viessmann Vitodens 300 Service Instructions Manual page 87

Repairs
(cont.)
Check the boiler temperature sensor, cylinder temperature
sensor or the flow temperature sensor for low loss header
1. Boiler temperature sensor: Pull the
leads from boiler temperature
sensor A and measure the resis-
tance.
Cylinder temperature sensor: Pull
the plug % from the cable harness
on the control unit and measure the
resistance.
Flow temperature sensor: Pull
plug X3 from the control unit and
measure the resistance across
terminals X3.4 and X3.5.
Troubleshooting
87