Operating and fault displays
Condens 7000 F – 6720871560 (2019/11)
50
B 7A 550 Voltage too low. The mains voltage is
too low.
The mains voltage must not fall
below 195 V.
Connect the correct power supply.
B 7A 551 Power failure. There has been a brief
interruption in the mains
voltage.
Check the mains cable for loose
contacts.
Check the wiring and correct
contacts of the mains plug at the
control unit and burner control unit.
Remedy any contact problems if
required.
B 7P 549 The safety chain
has opened.
The continuity of the
external components
integrated into the safety
chain has been
interrupted.
Check the continuity of the
components.
If required, replace faulty
components.
V or B 8L 534 No gas supply
pressure.
Flue gas pressure
limiter has tripped
Differential
pressure switch
has tripped.
Differential
pressure switch
defective.
The internal safety chain
(flue gas pressure limiter,
differential pressure
switch, valve testing
system) is open;
Fig. 74, page 61
Check that the gas isolator is open.
Check whether there is gas pressure.
Check whether the flue gas pressure
limiter has responded.
If the flue gas pressure limiter has
responded, check connections and
tightness of the flue system!
Check flue and combustion air pipe
for soiling (possible soiling of filter, if
installed) or blockage.
Check gas filter for contamination.
Check whether the differential
pressure switch has responded.
Check whether the valve testing
system has responded.
Measure gas pressure.
After resetting the flue gas pressure
limiter, find the cause of the trigger,
check the burner rod, check the
position of the ignition electrode,
check the condition of the ignition
electrode, check ignition spark,
check ignition cable contact.
Blow out burner rod against the flow
direction.
When using the “air filter” accessory
set, check the filter for
contamination. To do so, pull off the
PWM plug on the fan and when the
fan is running, check whether the
yellow warning is visible at the fill
level indicator.
If it is, replace the filter.
Test the differential pressure switch
(Chapter 16, page 54).
Replace the gas filter if necessary.
Replace the air/gas ratio control
valve if necessary.
B 8L 579 No gas supply
pressure.
Although the solenoid
valve 1 must have opened,
there is no gas supply
pressure. The burner
makes three successive
attempts at starting, then
waits for one hour before
making three more start
attempts.
Check that the gas isolator is open.
Measure the gas supply pressure.
Where required, Replace air/gas
ratio control valve.
If necessary, replace the air/gas ratio
control valve.
Check whether there is any gas
supply pressure.
V 8P 580 Solenoid valve 1
leaking.
The valve test system has
detected an unacceptably
high leakage rate on
solenoid valve 1.
Check the air/gas ratio control valve
for contamination.
Gas filter fitted.
Replace air/gas ratio control valve.
V 8U 581 Solenoid valve 2
leaking.
The valve test system has
detected an unacceptably
high leakage rate on
solenoid valve 2.
Check the air/gas ratio control valve
for contamination.
Gas filter fitted.
Replace air/gas ratio control valve.
B 8U 584 No diverter
module feedback
Diverter module does not
receive feedback within
the specified time.
No feedback from external
components.
Power cable damaged or faulty.
Faulty external component.
Check flue gas damper or other
connected component.
Check diverter module.
Check the plug-in connection.
Replace power cable if necessary.
Replace external component if
necessary.
Type
1)
Error
code
Sub-
code
Cause Description Test procedure/Cause Action
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