What does Fault Code Cd mean on my Viessmann B2TB004 Boiler?
If your Viessmann Boiler displays Fault Code Cd, there is a communication error with Vitocom 100 (KM BUS). Check connections, Vitocom 100 and coding address "95".
What does Fault Code dA mean on my Viessmann B2TB004 Boiler?
If your Viessmann Boiler displays Fault Code dA, there is a short circuit in the room temperature sensor for heating circuit 1 (without mixer). Check the room temperature sensor for heating circuit 1.
What does fault code 20 mean on my Viessmann Boiler?
If your Viessmann Boiler displays Fault Code 20, there is a short circuit in the system flow temperature sensor. Check the low loss header sensor.
What causes fault code A7 on a Viessmann B2TB004?
If your Viessmann Boiler displays fault code A7, it means the programming unit is faulty. Replace programming unit.
What does fault code bA mean on Viessmann Boiler?
If your Viessmann Boiler displays fault code bA, it indicates a communication error with the extension kit for heating circuit 2 (with mixer). Check extension kit connections and code.
Why is my Viessmann B2TB004 Boiler showing fault code bb?
If your Viessmann Boiler displays fault code bb, it indicates a communication error with the extension kit for heating circuit 3 (with mixer). Check extension kit connections and code.
What does error code E4 mean on my Viessmann B2TB004 Boiler?
If your Viessmann Boiler displays error code E4, it indicates a fault in the supply voltage of 24 V. To resolve this, replace the control unit.
What should I do if my Viessmann Boiler displays error code Fd?
If your Viessmann Boiler shows error code Fd, it indicates a burner control unit fault. Check the ignition electrodes and connecting cables. Verify that there isn't a strong electromagnetic interference (EMC) field near the equipment. Press reset button R. If the fault persists, replace the control unit.
Why does my Viessmann Boiler show error code Eb?
If your Viessmann Boiler shows error code Eb, it indicates that heat draw-off is repeatedly too low during calibration. Initiate a heat draw-off. Switch the boiler OFF and ON again. Press reset button R. Set coding address 12:1. This special function leads to heat being transferred to the heating circuit during calibration.
What does Fault Code E3 mean on my Viessmann B2TB004 Boiler?
If your Viessmann Boiler displays Fault Code E3, heat transfer is too low during calibration, and the temperature limiter caused a shutdown. Ensure adequate heat transfer and press the reset button R.
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