Worcester Highflow 3.5 OF Installation And Servicing Instructions page 17

(b) The Spark Electrode
Remove the main burner assembly, See lnstrucion
above.
( 1) Release the hexagon nut securing the spark electrode to
the pilot assembly and remove.
(2) Fit a new spark electrode. Check that the spark gap is
3 to 4 mm (0.14 in.). See Fig. 17.
(c)
The Pilot Shield
Remove the main burner assembly, See Instruction
above.
( 1) Remove the two M4 screws and nuts securing the pilot
shield to the pilot bracket.
( 2) Fit a new pilot shield and re-assemble in the reverse order.
(d) The Pilot Burner
Remove the main burner assembly. See Instruction 1.
( 1) Remove the spark electrode, pilot shield and injector as
described above.
(2) Remove the remaining M4 screw from the pilot bracket
and remove the pilot burner.
(3) Fit a new pilot burner and re-assemble in the reverse order.
Check that the pilot assembly is fitted above the mounting
bracket on the main burner.
4.
THE THERMOCOUPLE
(See Figs. 13 and 21.)
(a) Disconnect the thermocouple nut at the pilot bracket and
ease the thermocouple from the assembly.
(b) Release the thermocouple from its connection at the right
hand side of the gas valve.
(c) Remove the thermocouple from the boiler. To prevent the
risk of damage, remove the electrode lead before
removing the thermocouple.
(d) Re-assemble in the reverse order using a new
thermocouple. Avoid sharp bends in the thermocouple
lead, ensuring that it follows the same route as the original.
5. THE ELECTRODE LEAD
(See Fig. 21.)
(a) Carefully pull the lead off the connector tab at the
electrode and at the piezo unit.
(b) Remove the lead and fit a replacement.
6. THE COMBUSTION CHAMBER INSULATION
(See Figs .. 13 and 15.)
(a) Cover the burner and pilot with a clean cloth to prevent
any loose matter falling onto the assembly.
Fig. 18.
17
(b)
Remov~
the collector hood as described in Section 16,
Routine Cleaning.
(c) Drain the boiler.
(d) Loosen but do not completely remove, the two M5screws
at the top of each side of the combustion chamber
securing it to the inner casing.
(e) Release the union connections at the heat exchanger and
carefully manoeuvre the heat exchanger out of the inner
casing taking care not to mislay the fibre washers.
(f) Remove and discard the insulation and fit the replacement
pads, not forgetting the pad fitted to the combustion
chamber front cover.
(g) Refit the heat exchanger, not forgetting the union
washers, ensuring that it is correctly positioned.
NOTE: Do not forget to remove the cloth from the burner/pilot
assembly.
(h) Refit the combustion chamber cover.
(i) Tighten combustion chamber fixing screws.
(j) Re-assemble the appliance in the reverse order checking
that all the components have been fitted correctly.
The following components can be replaced if the cabinet
front panel is removed. See 17(b)
precedin~l·
7.
THE PIEZO GENERATOR
(See Fig. 21.)
(a) Carefully pull the lead off the connector tab at the piezo
generator.
(b) Remove the two M5 fixing screws and remove the piezo
generator.
(c) Fit a new generator and re-assemble in the reverse order
checking that the limit thermostat leads are not trapped
by the bracket.
Fig. 19.
Pilot Shield Pilot Spark Electrode