Viessmann Vitocrossal 300 Service Manual page 90

Troubleshooting
Corrective Action
90
(continued)
Vitocrossal 300 CU3A 26 to 57 Service
Extension kit for heating circuit with mixing valve
Checking the setting of rotary selector S1
The rotary selector on the PCB of the extension kit
defines the assignment to the relevant heating circuit.
Heating circuit
Heating circuit with mixing
valve M2 (heating circuit 2) 2
Heating circuit with mixing
valve M3 (heating circuit 3) 4
Note: The rotational direction of the mixing valve motor
during its self-test. Then set the mixing valve
manually to "Open".
Note: The supply temperature sensor must now capture
a higher temperature. If the temperature drops,
either the motor is turning in the wrong direction
or the mixing valve set is incorrectly fitted.
Checking the rotational direction of the mixing valve motor
After being switched on, the boiler implements a self-test.
During this, the mixing valve is opened and closed again.
Changing the rotational direction of the mixing valve
motor (if required)
1. Remove the upper casing cover of the extension kit.
WARNING
Electric shock hazard indicates an
imminently hazardous situation which,
if not avoided, may result in loss of life,
serious injury or substantial product /
property damage. Before opening the
boiler, disconnect main power.
2. At plug gS, swap the cores at terminals " " and " ".
3. Refit the casing cover.
Checking the Vitotronic 200-H (accessories)
The Vitotronic 200-H is connected to the control unit
via the LON cable. To test the connection, carry out a
participant check at the boiler control unit (see page 49).
Rotary selector S1 setting