Checking The Temperature Limiter - Viessmann Vitodens 222-F Installation And Service Instructions For Contractors

Troubleshooting
Maintenance
(cont.)
Fault "A3" during commissioning
During commissioning, the control unit checks whether
the flue gas temperature sensor is correctly positioned.
If the flue gas temperature sensor is not positioned
correctly, commissioning is cancelled and fault mes-
sage A3 is displayed.
1. Check whether the flue gas temperature sensor is
correctly inserted. See previous diagram.
2. If necessary, correct the position of the flue gas
temperature sensor or replace faulty flue gas tem-
perature sensor.

Checking the temperature limiter

If the burner control unit cannot be reset after a fault
shutdown although the boiler water temperature is
below approx. 75 °C, check the following:
Fig. 62
100
3. Press reset button R and repeat commissioning.
The check is repeated until it is completed suc-
cessfully.
Note
If a stable flame is not formed during the sensor test,
repeat the test several times.
1. Disconnect the leads from temperature limiter
2. Check continuity of the temperature limiter with a
multimeter.
3. Remove faulty temperature limiter.
A
4. Coat the new temperature limiter with heat con-
ducting paste and install it.
5. After commissioning, press reset button R on the
control unit.
.
A