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Faults and fault remediation
CFB 840
6 720 802 836 (2012/05)
22
Faults and fault remediation
Fault
Effect on control characteristics
Cause
Remedy
Outs.temp.
sensor
The minimum outside temperature is
applied.
•
The outside temperature sensor is either
incorrectly connected, e.g. not to the
control unit with address 1 in a multi-
boiler system, is not connected at all, or is
faulty.
•
Central module or control unit faulty.
•
Communication to control unit with
address 1 is interrupted.
B
Check whether the outside temperature
sensor has been connected to the correct
control unit (in multi-boiler systems to the
control unit with address 1).
B
Check communication with address 1.
B
Replace outside temperature sensor or
central module.
Flow sensor x
Mixing valve is no longer being
controlled.
•
Sensor is faulty or not connected.
•
An actuator (mixing valve) was selected
for the heating circuit.
B
Check sensor connection.
B
If the heating circuit with a fault should be
operated as an unmixed heating circuit,
check on the Programmer/service level/
heating circuit whether
Actuator no
is
selected (
Æ
DHW temp.
sensor
DHW heating has stopped.
•
Sensor faulty or not connected.
•
DHW has been selected.
•
Module or control unit faulty.
B
Check sensor connection.
B
Replace sensor or module.
B
Check sensor connection on DHW
cylinder.
B
Deselect DHW in the Programmer under
parameter DHW data if DHW heating is no
longer required (
Æ
chapter 11, page
35ff.).
DHW warning
•
There is a constant attempt at
charging the DHW cylinder with hot
water.
•
DHW priority is switched off after this
fault message is displayed.
•
Sensor faulty or not connected.
•
Constant drawing or system leak.
•
Manual switch not set to
AUT
.
•
Incorrect sensor arrangement.
•
Primary pump incorrectly connected or
faulty.
•
Module or control unit faulty.
B
Check sensor connection and values.
B
Fix any leakages.
B
Check whether the manual switch is to
AUT
.
B
Check primary pump function (e.g. with a
relay test
Æ
chapter 14, page 41).
B
Replace sensor or module.
DHW cold
DHW heating was interrupted. Current
DHW temperature is below 40 °C.
•
Primary pump faulty.
•
More DHW is removed than newly heated.
B
Check whether the temperature
controller is set to a sufficiently high value
(e.g. factory setting: 90 °C) or whether
the manual switch is set to
AUT
.
B
Check function of sensor and cylinder
primary pump.
B
Check sensor connection on DHW
cylinder.
Therm.
disinfect
Thermal disinfection was interrupted.
•
Too much water drawn during thermal
disinfection.
•
Boiler output is temporarily insufficient
due to heat drawn by other consumers
(e.g. heating circuits).
•
Sensor faulty or not correctly connected,
or primary pump faulty.
•
Module or control unit faulty.
B
Select pasteurisation at a time when no
other heat demand is made.
B
Check sensor and primary pump function
and replace if necessary. (
Æ
chapter 14,
page 41, chapter 2.7, page 5).
B
Replace module or control unit if
required.
Remote control
x
Because no actual room temperature is
available, the effect of the following
features is disabled: Room influence,
start and stop optimisation, and
automatic adaptation.
•
The remote control unit is incorrectly
connected or faulty.
•
Incorrect address allocated to remote
control.
•
Remote control cable damaged or
broken.
B
Check function/connection of remote
control. Also check the address of the
remote control.
B
Replace remote control/function module.
B
Also check the address of the remote
control.
B
Check connecting cables.
Table 88 fault overview
