Check Fixed High Limit; Check Flue Gas Temperature Sensor - Viessmann VITODENS 100-W Installation And Service Instructions Manual

Troubleshooting
Correction
(continued)

Check fixed high limit

A
Fig. 71

Check flue gas temperature sensor

A
Fig. 72
70
If the burner control unit cannot be reset after a fault shutdown (F2), even
though the boiler water temperature is below approx. 203°F / 95°C, check the
fixed high limit.
20
10
8
6
4
2
1
0,8
0,6
0,4
10 30 50 70
50 86 122 158 194 230 ºF
Temperature
1. Pull the leads from fixed high limit
.
2. Check the continuity of the fixed
high limit with a multimeter.
3. Remove faulty fixed high limit.
4. Coat the replacement fixed high limit
with heat conducting paste and
install.
5. To reset, refer to page 66.
1. Pull the leads from flue gas
temperature sensor
2. Check the sensor resistance and
compare it with the curve.
3. Replace the sensor in case of severe
deviation.
90 110 ºC
.