Worcester 350 Combi User Manual

6. Spark Electrode. See Figs. 9b and 35.
Check that the electrical supply has been turned off .
Remove the inner casing cover and facia . See Section 13.3. (c) and
14.2
(a) .
Pull off the lead from its tab on the ignition board. See Fig. 9b.
Unscrew the securing nut holding the electrode to its mounting
bracket and withdraw the electrode and lead.
See Fig . 35.
Fit a new electrode assembly in the reverse order. Check that the
electrode tip
is the correct height above the burner blade. See Fig.
35.
7. Flame
Sensing Electrode. See Figs . 9b and 35.
Check that the electrical supply has been turned off .
Replace the electrode as described in Section 14.4.6 preceding.
8.
Gas Valve . See Figs . 9b and 26.
Check that the electrical supply has been turned off.
Lower the control box. See Section 14.2 (b). Remove the cabinet
bottom panel by unscrewing the two
screws . See Fig . 22 .
Pull off the suction pressure compensating tube. See Fig. 26.
Unscrew and move aside the main solenoid cover on the gas valve.
Carefully disconnect the leads from the two solenoids and the
Modureg head on the gas valve and unscrew the earth lead.
Unscrew the four screws securing the flange at the top of the gas
valve.
Unscrew the union connection at the mounting manifold
and
remove the gas valve.
Transfer the inlet pipe and gaskets to the new valve .
Fit the new valve ensuring that the two gaskets are seated in their
housings.
Fit a new valve in the reverse order. See Fig . 9a.
To replace the Modureg head only
Pull off the suction pressure compensating tube and the electrical
connections.
Unscrew the two screws securing the Modureg head
to the main body and remove.
Fit the new Modureg head (Honeywell 2032) in the reverse order
ensuring
that the gasket is in the correct position. Transfer the
compensating tube connection.
Test for gas soundness at all joints as described in Section 11 .2.
To set the burner pressure. See Fig . 26.
The minimum and maximum burner pressures must be set after a
new gas control has been fitted.
Follow the procedure described
in Section 11 .4 - Appliance
Start-Up.
The minimum burner pressure must be set first as any adjustment
of the minimum pressure influences the maximum pressure set·
tin g.
Remove the fixing screw and remove the Modureg head cover.
Remove the compensating tube from the gas valve. See Fig . 26.
Th e tube and the Modur eg cap, must be replaced immediat ely the
adjustments have been made to ensure the proper operation
of
the gas control.
Remove a lead from the Modureg control and start the appliance
in the domestic hot water mode as described in Section 11 .5 -
Appliance Operation. Adjust the minimum pressure adjustment
nut to
give a burner pressure of 1 .3 mbar. See Fig . 2 6.
Switch o ff the applian ce and turn off the electricity supply. Refi t
the lead to the
Modureg head.
Switch on the electricity supply to the appliance and re - light in the
domestic hot water mode.
The burner pressure will immediately
increase to the maximum.
Turn the maximum pressure adjustment screw until the burner
press
ure is 14.5 mbar. See F ig . 26. The operating pressure of 14.2
mb ar is obtained when the compensating tube is re fi tted to the
gas
valve .
It should not be necessary to alter the central heating potentiome-
ter setting when the gas control is replaced and the minimum and
maximum burner pressures are set.
24
Fig. 33. Air flow pressure switch.
P ress ure tube conne ct ions
I P2 at the fr ont, Pl at the r ear )
Swit ch fi xin g sc re ws 121
Tennin al3 (whi te )
M
ou n ting bracket
Tenn i na l 2 ( no rmall y open ) Tenn inall l norma lly cl ose d)
(b ro wn ) ( green )
Fig. 34. Overheat thermostat.
The rm o stat phi al clip
Thermostat poc ket an d p hial
0
Fig. 35. Electrode fixing and gap setting.
(SPARK ELE CTRODE SHOWN )
Electrode Gap Settings
Spark electrode- 3.5 mm (± 0.5 mm ). Left h an d side of burn er.
Flame setting e lectro de- 3 mm (± 1 mm) . Ri gh t ha nd side of burner.
I
C
Electrode bra ck et fi x in g s cr ews ( 2)
1
El ect rode lead integ ral w ith th e e lect rod e
E
lectrod e bracket lowe r fixing s crew

Worcester 350 Combi Specifications

General

Brand	Worcester
Model	350 Combi
Category	Boiler
Language	English