Symptoms
5
We reserve the right to make technical modifications
Buderus Ltd. • http://www.buderus-domestic.co.uk
18
Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
box 20
Display codes
Display indication
z
Display
code
Key to display code
Reset
required?
Other symptoms
Diagnosis
[//]
No indication on DBA control panel display.
[//)
Standby
Hot water mode to “warm start”.
C
[0h]
No (or insufficient) hot water, radiators, convectors,
etc. may be heated without current heat requirement.
C
[0h]
Standby
Applies to boilers with hot water supply,
hot water available, no heating operation.
Applies to boilers without hot water supply,
no heating operation.
C
[0h]
Standby
Applies to boilers with hot water supply,
hot water available, no heating operation.
C
:-h.
Operating phase:
The boiler is in heating mode.
C
:=h)
Operating phase:
The boiler is in hot water mode. The symbol “
G
” lights up.
The heating circuit is warmed up without a heat
requirement.
C
[0a]
Operating phase:
Pump over-run time via the external cylinder/hot water
heater. The symbol “
G
“ is off.
Pump over-run time:
Heating system factory default setting = 5 minutes;
for details of hot water and service mode see box 5.
C
[0a]
Operating phase:
The switch optimisation program is activated. This
program is activated if there is, more frequently than once
every 10 minutes, a heating water requirement from an
RC or ON/OFF control signal. This means that the boiler
cannot be restarted until at least 10 minutes have elapsed
since initial startup of the burner.
The target room-temperature may not be reached.
C
[0c]
Pre-operative phase:
The boiler prepares for burner startup whenever a heating
requirement or hot water requirement arises.
C
[0e]
Ready for operation:
The boiler is in ready mode. There is a current heat
requirement, but too much energy has been supplied.
C
[0h]
Standby for operation:
The boiler is in ready mode.
There is no current heat requirement.
Heat request, but no respons of the boiler
C
[0l]
Ignition phase:
The gas valve is activated.
C
[0u]
Startup phase:
The boiler starts up after activation of the mains power
supply or completion of a system reset. This code is
displayed for a maximum of 4 minutes.
Recycling phase:
The fan runs for 15 seconds at about 60% of
maximum speed.
"Extraction of residual fumes in boiler"
C
[0y]
Operating phase:
The flow sensor has detected that the current CH flow
temperature is higher than the temperature entered at the
control unit, or that it is higher than the CH flow tempera-
ture calculated according to heating requirements, or that
it is higher than the CH flow temperature calculated for the
purposes of hot water supply.
The target room-temperature may not be reached.
C
[0y]
Fault:
The flow sensor or safety sensor has detected that the
current CH flow temperature is higher than 95°C.
No
1)
The target room-temperature may not be reached.
?1c]
Fault:
The flue-gas STL (fume-monitoring device) has detected
a temperature higher than 105°C.
The flue-gas STL is opened.
Yes
2)
No heating operation and no hot water.
C
[2f]
Fault:
The flow sensor and safety sensor have, after burner
startup, not detected any temperature increase in the
heating water, or they have determined that the
temperature difference between The flow sensor and
safety sensor is too high.
No
1)
1) This error code may deactivate again automatically after a specific time (without reset). Heating and hot water are now available once more.
2) In the event of this malfunction, the pump is started up and remains in continuous operation in order to minimise the possibility of the heating system
freezing up.
