47
é
2
Return tempera-
ture is higher
than the flow
temperature
Insufficient water.
Check the water level and check for leaks.
No through flow.
Check that the pump is working; turn the spindle with a screw-
driver, if that works but the pump still does not respond, check
the wiring; that is in order the pump is faulty.
Too much air in the system.
Vent the system.
Sensors not wired correctly
Check the wiring between sensors and control unit.
Pump operating in wrong direction Check wiring from and to control unit.
Flow and return connections
crossed
flow and return connections
Deviation in the flow or return tem-
perature sensor.
Check that the sensors are working; take the sensors out* and
measure the resistance with a multimeter at room temperature
(20 - 25°C); the sensor is working properly if the resistance is
between 12 and 15 kΩ
é
3
Control unit or
earth fault
Mains supply not correctly
earthed.
Control unit faulty.
Check that the power supply from the switch spur is properly
earthed, if that is the case the control unit is faulty.
é
4
More than 5 start
attempts without
any flame forma-
tion.
No ignition spark.
Check:
•
the connection between the ignition wire and the ignition
trafo;
•
the ignition wire and electrode for ‘dielectric breakdown’;
•
the inter-electrode distance, this should be 3-4 mm; that
weather the ignition electrode is properly earthed.
A spark but no flame.
Check that:
•
the gas tap is open;
•
the gas pre-pressure is sufficient;
•
the gas pipe is de-aerated;
•
the gas valve is energised during ignition and opens;
•
the electrode is correctly fitted and clean;
•
the CO
2
adjustment at low and full load;
•
there is no obstruction / fitting fault in the gas pipe;
•
there is no obstruction in the air supply or flue (e.g. a
blocked siphon); there is no recirculation of flue gasses
(either inside or outside the boiler).
There is a flame but no, or insuf-
ficient ionisation (lower than 3 or
higher than 9
µ
A)
Check:
•
the flame, is the heart of the flame visible and the flame
stable?
•
the CO
2
adjustment at low and full load;
•
that the ignition electrode is correctly earthed;
•
visual check of the ignition/ionisation electrode: look for
white oxide film (remove with sandpaper or a screwdriver);
look at the shape (are the pins still the original shape and
is the distance between the two ends of the pins between 3
and 4 mm).
é
5
No ionisation or
ionisation failure
more than 5
times during one
heat demand.
CO
2
wrongly adjusted
Check:
•
CO
2
adjustment on the gas block;
•
Ignition/ionisation pin;
•
Flue/air-supply connections;
•
Gas flow at full load;
•
If there is no recirculation of flue gasses (either inside or
outside the boiler).
é
6
Unwanted flame
formation
Ignition Unit
Faulty ignition unit, replace ignition unit.
Control unit
Faulty control unit, replace control unit.
é
7
No water in the
boiler or the
pump is not
working
Insufficient water.
Check the water level and check for leaks.
No through flow.
Check that the pump is working; turn the spindle with a screw-
driver, if that works but the pump still does not respond, check
the wiring; that is in order the pump is faulty.
Too much air in the system.
Vent the system.
Pump operating in wrong direction. Check wiring from and to control unit.
Pump not running
Check wiring, connections and pump
