Viessmann VITOPEND 100-W Installation And Service Instructions Manual page 36

Troubleshooting
Repairs
(cont.)
A Outlet temperature sensor (gas
fired combi boiler)
B Boiler water temperature sensor
C Temperature limiter
1. Boiler water temperature sensor:
Pull the leads from the sensor.
Check the sensor resistance and
compare it with the curve.
Replace the sensor in case of
severe deviation.
!
Please note
The boiler water temperature
sensor is immersed in the
heating water (risk of scald-
ing).
Drain the boiler before repla-
cing the sensor.
36
D Flue gas monitoring sensor
% Cylinder temperature sensor (gas
fired central heating boiler)
2. Temperature limiter:
Check the temperature limiter, if
the burner control unit cannot be
reset after a fault shutdown,
although the boiler water tempera-
ture is below approx. 90 °C.
Pull the leads from the sensor.
Check the continuity of the tem-
perature limiter with a multimeter.
Remove the faulty temperature
limiter.
Coat the replacement tempera-
ture limiter with heat conducting
paste and install it.
To reset, briefly turn rotary selec-
tor "tr" fully clockwise and then
back again. The ignition proce-
dure will then be repeated.