Check Fixed High Limit; Extension Kit For Heating Circuit With Mixing Valve; Check The Vitotronic 200-H (Accessories) - Viessmann VITODENS 200-W Service Instructions Manual

Vitodens 200-W B2HA 19, 28, 35 Service
Corrective Action
Heating circuit
Heating circuit with mixing
valve M2 (heating circuit 2) 2
Heating circuit with mixing
valve M3 (heating circuit 3) 4
(continued)
Rotary selector S1 setting

Check fixed high limit

Check the fixed high limit, if the burner control cannot be
reset after a fault shutdown, although the boiler water
temp. is below approx. 167°F (75°C):
1. Remove cables from the fixed high limit A.
2. Check the continuity of the fixed high limit with a
multimeter.
3. Remove and replace a defective fixed high limit.
4. After starting up the boiler, press reset button R on
the boiler control.

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.
Note: The rotational direction of the mixing valve motor
during its self-test. Then set the mixing valve
manually to "Open".
Note: The flow 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, switch 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. To test the connection, carry out a participant
check at the boiler control unit (see page 37).
Troubleshooting
81