Heatrae Sadia FBM 25 ECO 3KW, Installation, Operation And Maintenance Manual, Page: 26 / 40

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10. Troubleshooting
Fault Possible cause Remedy
No hot water flow
No cold water supply
Check that there is cold water to the
property
Cold water supply off Check and open stop cock
Hot water Isolating valve turned off Turn on the isolating valve.
Cold water control valves incorrectly
fitted
Check and refit as required
Water heater water level dropped
below the hot outlet pipe inside the
tank
Check level sensor connections and
remove any build-up of scale
Solenoid valve non operational Check electrical connections
Water appears in the tundish
Water sensing inside the water heater
has failed, both the level and overfill
sensing.
Check the sensor wiring
Check the control PCB, if the PCB
is suspected as being faulty replace
and then check operation
Solenoid valve has failed in the open
state
Replace the solenoid valve
Scale build up Remove scale
Water leaking from the water heater
Corrosion causing internal damage
Turn off the power, turn off the water
supply, drain unit and investigate the
fault
Leaking pipe work
Turn off the power, turn off the water
supply, drain unit and investigate the
fault
Leaking immersion seal
Turn off the power, turn off the water
supply, drain the unit, remove the
immersion and replace the seal
Steam rising from the tundish
Water heater temperature set point
set to maximum
Verify that this is the required
temperature, if not, return set point to
required level
Thermostat failure Replace the thermistor
Electronic cut out failure Replace the cut out
Water heater fails to power up
Power supply failure
Check the supply to the fused spur
Check the fuse in the spur
Check the wiring and connections
Check the control PCB
Overheating electrical connections
Ensure electrical connections
are tight, replace any damaged
connections
Overheating on control PCB
Turn power off, Investigate fault
Replace PCB if required
The fault finding table below will enable operational faults
to be identified and their possible causes rectified.

If a fault code is displayed on the controller refer to
the fault codes in table 10 on pages 27 and 28 for details.
Table 9: Fault finding table
10.1 Fault Finding