23
2000225005B
IMPORTANT.
On completion of the Fault Finding task which
has required the breaking and remaking of the electrical
connections, the continuity, polarity, short circuit and resistance
to earth checks must be repeated using a suitable multimeter.
WARNING.
The multifunctional control and fan operate on
mains voltage, the terminal will be live.
9.1 Electrical
Gain access to the control box, refer to the relevant paragraph
in section 6.1, then remove the control box cover, refer to
section 5.1.
Refer to: Boiler Fault Finding, see diagram 9.2, Fault Finding
Wiring Diagram, see diagram 9.3, Pictorial Wiring Diagram, see
diagram 9.4.
Diagram 9.2
ELECTRICAL FAULT FINDING
Diagram 9.1
9917
BOILER
TEMPERATURE
CONTROL
0900
Check for 230V ac
between N and common
contact on air
pressure switch.
With electrical supply isolated remove the fan access door as
described in the relevant parts of section 8.1, to gain access to the
air pressure switch. Switch on electrical supply Check for 230V ac
between N and normally closed contact of air pressure switch.
Is there 230V ac between
Ls and N
Ensure that any external controls are calling for heat and circuit water is cold.
If neon 6 is lit flame failure has occured. Reset boiler by turning temperature control to Off,
waiting 30 seconds and then on.
If fault persists continue with fault finding below.
Before carrying out fault finding, ensure that gas, electricity and water are available at the boiler.
Is neon 1 lit?
NO
Check power supply
Is neon 2 lit?
NO
YES
YES
Faulty thermistor.
Replace.
With electrical supply isolated
disconnect the 2 way
thermistor plug from the PCB.
Check that there is a resistance
between 14k - 2.5kOhms.
Faulty PCB.
Replace.
Is neon 3 lit?
Faulty PCB.
Replace.
YES
NO
NO
YES
YES
Faulty air pressure
switch. Replace.
Does sparking take place
(Listen for spark discharge.)
?
Faulty PCB.
Replace.
Check for 230V ac
between N and brown
and between N and black,
3 way connector on PCB.
Faulty PCB.
Replace.
NO
NO
Check continuity of
gas valve harness.
Faulty gas valve.
Replace.
Faulty harness.
Replace.
NO
YES
NO
Is the fan turning?
YES
NO
Is there 230Vac
on fan?
Faulty
PCB.
Faulty
fan.
Does burner light?
YES
YES
YES
YES
NO
NO
Is neon 4 lit?
NO
YES
Appliance working
satisfactorily.
Is integrity of
electrode and
HT lead good?
Replace as
necessary
Faulty
PCB.
YES
NO
YES
NO
NO
9 Fault Finding