Zanussi ULTRA COMBI 35 Installation And Servicing page 55

72 ALTERNATING 'L' AND '1' - FLOW TEMPERATURE OVERHEAT LOCKOUT
Is the Boiler and CH System filled with water and all
isolation and radiator valves open?
Is the Flow/Return Differential across the Boiler in
excess of 30°C?
Check the Return Thermistors
(Refer to Frame 47)
Check resistance using a suitable multimeter
connected across the thermistor's terminal pins
At 25 C expect
o
At 60 C expect
o
At 85 C expect
o
73 ALTERNATING 'L' AND '2' - IGNITION LOCKOUT
If the boiler is restart does the
boiler ignite for a short time and
then extinguish?
YES
Check the detection electrode
and associated harness for:
continuity, visual condition and
position (Refer to Frame 49).
Check if the condensate pipe is
blocked.
Check flue is installed correctly.
Replace as necessary
Check siphon and condensate
drain pipe work for blockage and
rectify if necessary. Boiler now
working OK?
NO
Replace Gas Valve
* Note: due to the wave form of the rectified voltage, the reading will vary depending on the type of meter used to measure the
value. In general terms a reading greater than 150V indicates that the correct voltage is supplied to the gas valve.
RESET PROCEDURE - To restart boiler, turn mode knob to restart position and immediately turn knob back to required setting.
Installation and Servicing
FAULT FINDING
YES
NO
9,700 - 10,300 Ohms
2,400 - 2,600 Ohms
1,000 - 1,100 Ohms
NO
Is the Gas Pressure available at
the Boiler Inlet (>18 mbar)?
Is 215Vdc supply available at the
Gas Valve? (* See note)
Unplug gas valve. Is resistance
between outside pins between 4k
Ω (± 2)?
Check spark generator and
associated harness for: continuity
and visual condition. (Refer to
Frame 50) Are these functioning
correctly?
Check ignition electrode and
YES
associated harness for: continuity,
visual condition and position.
(Refer to Frame 48) Are these
functioning correctly?
NO
Fill and vent the system and open all
isolation valves, then restart boiler
YES
Check that the Pump is rotating freely. Is
the Differential now below 20°C?
NO
Replace the Pump,
then restart boiler
RESET PROCEDURE - To restart boiler, turn mode knob to restart
position and immediately turn knob back to required setting.
YES
YES
YES
YES
YES
OK, now
restart boiler
NO
Check gas supply and
rectify fault
Check wiring connection
NO
from gas valve to PCB for
continuity. If the wiring is
OK then replace the PCB
NO
Replace Gas Valve
NO
Replace Spark
Generator and harness
as necessary
Replace Ignition
NO
Electrode and
associated harness as
necessary
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