Viessmann Vitocrossal 300 Service Instructions For Contractors page 109

Repairs
(cont.)
20
10
8
6
4
2
1
0.8
0.6
0.4
10 30 50 70 90 110
Temperature in °C
Checking the temperature limiter
If the burner control unit cannot be reset after a fault shutdown, although the boiler
water temperature is below approx. 85 °C, check the following:
47
1. Pull the leads from temperature lim-
iter fJ.
2. Check the sensor resistance and
compare it with the curve.
3. Replace the sensor in the case of
severe deviation.
2. Check the continuity of the tempera-
ture limiter with a multimeter.
3. Remove the faulty temperature lim-
iter.
4. Coat the replacement temperature
limiter with heat conducting paste
and install it.
5. After commissioning, press reset but-
ton R on the control unit.
Troubleshooting
109