Viessmann VITOTRONIC 300 Installation And Service Instructions Manual page 78

Mixer circuit extension kit
Changing the rotational direction
H
H
¨ Safety instruction
Switch OFF the mains power supply before opening the device.
Switching the mains switch on the mixer extension OFF is not safe enough.
A
B
78
must
B
A
1.
2.
3.
Relay test
H
H
H
H
Please note:
A relay test is implemented every
time the system is switched ON.