Boulter Buderus Benchmark 600-28C Installation And Servicing Instruction page 39

Servicing
Code Meaning
2U Non blinking fault code: Temp. difference between the bi-sensor and the return sensor is greater than 50 °K
Possible
cause
1 Resistance in the installation is too high
2 Water pressure is too low in the installation
3 Problem with the pump or pump cabling
(no circulation)
4 Bi-sensor is dirty or faulty
5 Return sensor may be faulty
Code Meaning
3A Non blinking fault code: No communication between fan and UBA
Possible
cause
1 Faulty cable or connection
2 Fan is defect
Code Meaning
3L Blinking fault code: Fan signal not detected at power up stage
Possible
cause
1 Faulty cable or connection
2 Fan is defect
Code Meaning
3P Blinking fault code: Fan running too slow
Possible
cause
1 Fan may be dirty
2 Power supply may be faulty
3 Fan wiring or connections faulty
Subject to modifications resulting from technical improvements!
Installation and maintenance instructions for wall-mounted condensing gas boiler 600 - 28C • 01/2004
Action
Check if not all (thermostatic) radiator valves are closed or
clogged with dirt
Top up the system (see subsection 2.1.1)
Check if the pump cabling is faulty or if the pump is stuck.
Replace pump when necessary (see subsection 5.3.6 and
subsection 5.3.7)
Check the bi-sensor for dirt. Measure if resistance over the
sensor is correct. If not replace bi-sensor (see subsection
5.3.8, subsection 5.3.9, subsection 5.3.10)
Check return sensor and when necessary replace sensor
(see subsection 5.3.8)
Action
Check the cabling and connections and replace when
necessary (see subsection 5.3.3)
Replace fan (see subsection 5.3.3)
Action
Check the cabling and connections and replace when
necessary (see subsection 5.3.3)
Replace fan (see subsection 5.3.3)
Action
Check fan for dirt (see subsection 5.3.3)
Check the power supply
Check the fan wiring and connections
(see subsection 5.3.3)
Boulter Buderus Ltd. • http://www.boulter-boilers.com
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