Viessmann Vitodens 200 Start-Up/Service Instructions page 41

Vitodens 200 WB2 Service
Correction
(continued)
Check safety fixed high limits (FHL)
If the safety fixed high limits cannot be reset after an
automatic lockout of the burner control unit, even though
the boiler water temperature is below approx. 194ºF /
90ºC, perform the following steps:
Disconnect one cable from each of the fixed high limit
switches A.
Check continuity of the fixed high limit switches with
a multimeter.
Remove defective limit switches.
Coat new limit switches with heat conductive paste
and install.
After start-up, press the reset button "EU" on the
control unit.
Check fuse
1. Disconnect connector fÖ A in the control unit.
2. Remove fuse F3 (6.3 A) B by holding its grip and
pulling out of the base.
3. Check continuity of fuse with a multimeter.
Check thermostatic radiator valves
Check operation and setting.
IMPORTANT
The thermostatic radiator valves must not be activated in
a room in which the room temperature sensor is installed
for room temperature dependent operation.
In case of a weather-responsive control, with a room
temperature sensor via the RS remote control unit, keep
the thermostatic radiator valves fully open.
Troubleshooting
41