Servicing
5
38
Installation and maintenance instructions for wall-mounted condensing gas boiler 600 - 11S/19S/24S/24C • 02/2006
Buderus • http://www.buderus-domestic.co.uk
Subject to modifications resulting from technical improvements!
Code
Meaning
3C
Bad plug-in connection at cable harness, or damaged wiring
Possible
cause
Action
1
Cable harness is faulty
Check cable harness for faults and bad connections
2
Connectors at the back of the UBA are loose or faulty
Check the connectors at the back of the UBA
3
UBA might be faulty
Check the UBA by temporarily connecting an other UBA
(see subsection 5.3.3)
Code
Meaning
4A
Flow sensor exceeds 100 °C
Possible
cause
Action
1
Flow sensor is dirty or faulty
Check the sensor, replace if necessary (see subsection
5.3.14, subsection 5.3.15, subsection 5.3.16)
2
There is a problem with the pump or pump cabling
(no circulation)
Check if the pump cabling is faulty or if the pump is stuck.
Replace pump if necessary (see subsection 5.3.9 and
subsection 5.3.10)
3
Water pressure is too low in the installation
Top up the system (see subsection 2.1.1)
Code
Meaning
4C
F2 fuse malfunction, or flue gas thermostat active
Possible
cause
Action
1
Water pressure is too low in the installation
Top up the system (see subsection 2.1.1)
2
Heat exchanger is dirty
Check for a dirty heat exchanger and clean if necessary.
(see subsection 4.1)
3
Flue gas retarder faulty or missing
Check if the flue gas retarder is installed in the heat
exchanger
4
Heat exchanger has a problem
Purge heat exchanger
Code
Meaning
4F
Flow sensor exceeds 100 °C
Possible
cause
Action
1
Resistance in the installation is too high
Check if not all (thermostatic) radiator valves are clogged
with dirt
2
Heating capacity is too large for the installation
Adjust the heating capacity
3
Safety sensor is faulty
Check the sensor and measure if resistance over the
sensor is correct. If not replace safety sensor (see
subsection 5.3.11, subsection 5.3.12, subsection 5.3.13)
4
Problem with the pump or pump cabling (no circulation)
Check if the pump cabling is faulty or if the pump is stuck
(see subsection 5.3.9)
5
Water pressure is too low in the installation
Top up the system (see subsection 2.1.1)
Code
Meaning
4H
System error
Possible
cause
Action
1
Boiler is in operation for DHW due to a dripping faucet
Check for dripping faucets