Viessmann Vitocrossal 300 CA3 2.5 Installation And Service Instructions Manual page 181

Vitocrossal 300 CA3 Series 2.5 to 6.0 Installation/Service
Boiler System Fault Codes
Displayed System characteristics
fault code
b6 Constant mode
b7 Boiler water temperature control
b8 Control mode
ba Mixing valve close
bc Control mode without
remote control.
bd Control mode without
remote control
be Control mode without
remote control
bf Control mode
No communication via LON
c1 Boiler cools down
c2 Control mode
c3 Control mode
c8 Boiler cools down.
(continued)
Cause
Invalid hardware recognition
Coding card fault
Lead break, flue gas temperature
sensor
Communication error, PCB,
extension for heating circuits 2
and 3 with mixing valve.
Communication error, Vitotrol
remote control unit, heating
circuit without mixing valve A1
(heating circuit 1).
Communication error, Vitotrol
remote control unit, heating
circuit with mixing valve M2
(heating circuit 2)
Communication error, Vitotrol
remote control unit, heating
circuit with mixing valve M3
(heating circuit 3)
Incorrect LON communication
module.
External safety equipment at plug
aBÖ.
Lead break, KM BUS to solar
control module, type SM1 or
Vitosolic.
Communication error, AM1
extension
Fault, low water indicator at
"X7" of plug-in adapter 1 for
external safety equipment.
Troubleshooting
Measures
Check coding address "92" in
the "General" group;
H 161: Single boiler system
H 190: Cascade control unit
H 166: Boiler section 2/boiler
section 3 control unit
Note: Coding "8a:176" in the
"General" group must be set in
order for coding "92" to be able
to be displayed.
Plug in or replace the boiler
coding card.
Replace temperature sensor.
Set code "1F:0" in the "Boiler"
group.
Check that the PCB and ribbon
cable are plugged in correctly,
and replace PCB if required.
Check connections, lead (see
separate installation and service
instructions) and coding address
"a0" in the "Heating circuit..."
group.
Check connections, lead (see
separate installation and service
instructions) and coding address
"a0" in the "Heating circuit..."
group.
Check connections, lead (see
separate installation and service
instructions) and coding address
"a0" in the "Heating circuit..."
group.
Replace LON communication
module.
Check connection and external
safety equipment.
Check KM BUS cable and
appliance.
Without solar control unit:
Set code "54:0" in the "General"
group.
Check connections.
Without AM1 extension:
Set coding "32:0" in the
"General" group.
Check system water level, reset
low water indicator.
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