Buderus 600-19R Installation And Servicing Instructions page 33

Servicing
Code Meaning
2U
Temperature difference between flow and return more than 55 °C
Possible
cause
1 Flow sensor is dirty or faulty
2 Problem with the pump or pump cabling (no circulation)
3 Water pressure is too low in the installation
4 Resistance in the installation is too high
5 Safety sensor is dirty or faulty
Code Meaning
3C
Bad plug-in connection at cable harness, or damaged wiring
Possible
cause
1 Cable harness is faulty
2 Connectors at the back of the UBA are loose or faulty
3 UBA might be faulty
Code Meaning
4A
Flow sensor exceeds 100 °C
Possible
cause
1 Flow sensor is dirty or faulty
2 There is a problem with the pump or pump cabling
(no circulation)
3 Water pressure is too low in the installation
Code Meaning
4C
F2 fuse malfunction, or flue gas thermostat active
Possible
cause
1 Water pressure is too low in the installation
2 Heat exchanger is dirty
3 Flue gas retarder faulty or missing
4 Heat exchanger has a problem
Subject to modifications resulting from technical improvements!
Installation and maintenance instructions for wall-mounted condensing gas boiler Buderus 600 - 11R/19R/24R • 05/2004
Action
Check the sensor, replace if necessary (see subsection
5.3.11, subsection 5.3.12, subsection 5.3.13)
Check if the pump cabling is faulty or if the pump is stuck.
Replace pump if necessary.
Top up the system
Check if not all (thermostatic) radiator valves are closed or
clogged with dirt
Check the safety sensor for dirt. Measure if resistance over
the sensor is correct. If not replace safety sensor (see
subsection 5.3.8, subsection 5.3.9, subsection 5.3.10)
Action
Check cable harness for faults and bad connections
Check the connectors at the back of the UBA
Check the UBA by temporarily connecting an other UBA
(see subsection 5.3.3)
Action
Check the sensor, replace if necessary (see subsection
5.3.11, subsection 5.3.12, subsection 5.3.13)
Check if the pump cabling is faulty or if the pump is stuck.
Replace pump if necessary.
Top up the system
Action
Top up the system
Check for a dirty heat exchanger and clean if necessary.
(see subsection 4.1)
Check if the flue gas retarder is installed in the heat
exchanger
Purge heat exchanger
Boulter Buderus Ltd. • http://www.boulter-buderus.co.uk
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