Worcester 350 Combi User Manual

14. Replacement of Parts
14 .1. WARNING.
Switch off the electricity and gas supp li es before replacing any
components.
After
the replacement of any components, check for gas sound-
ness where relevant and carry out functi ona l checks as desc ri bed
in Section 11 .
14.2. COMPONENT ACCESS.
To replace components it is necessary to remove one or more sec-
tions of the cab in et and cover plates within the appliance as
described in Section 13.3 together with the facia and control box
as described in the notes fo llo wing.
(a) Facia. Remove the inner cover pane l as described in Section
13.3 (b) . Remove the three screws which hold the facia assem-
bly in position. Lower the fascia assembly. The assembly can
be unhooked from its supports.
Do n ot allow it to hang unsup-
ported. See Fig . 20.
(b) Control Box. Remove the inner cov er pane l as described in
Section 13.3 (b) . Unscrew the two fixing screws at each end of
the control box.
Pull the complete assembly forward and lo wer
if necessary. The assembly can be unhooked from its support s.
Do not allow it to hang unsupported. See Fig . 22.
Important : The fo llo wing components are secured to the appli-
ance with clips. See Figs. 37 , 38 and 39 .
12 : Expansion Vessel
13: Central Heating Pump
14: Domestic Hot Water Pump
15: Wa ter to Water Heat Exchanger
27: Gas to Water Heat Exchanger
Important : Co mprehensive gasket/ 0-ring packs are available for
the gas and water connections on the appliance. See Section 15.
When replacing
th ese components the connections must be fully
entered so
that the clips can pa ss completely into t he locating
groove.
The clips must not be forced into place.
Any
'0' ring which shows sign of damage must be replaced. Th e
'0 ' rings can be lubricated wi th a suitable lubricant (i.e . silicon
based grease or glycerin) which is non-reactive with the eth y-
lene- propylene nit ril e '0 ' rings.
14.3. DRAINING THE APPLIANCE
Check th at the electricity supply to the appliance is turned off.
Before removing any compon ent holding water , it is impo rt ant
that as much wa ter as poss ibl e is removed from the appliance.
(a) Appliance Central Heating Circuit
Turn off the central heating flow and return valves at the app li -
ance. See Figs. 21 and 28. These are operated us ing an
adjustable s pa nn er or a screwdriver.
Fit a tube to the drain tap and open the tap about one turn.
See Fig . 28 . Pre ss in the non-return valve test button on the
central he at ing pu mp (left hand) to remove more water. See
Fig . 39. Close the drain tap when the flow has stopped.
Some water will remain in the expansion vessel, pumps and
Gas to Water he at exch anger and extra care must be taken
when removing these components.
(b) Appliance Hot Water Circuit
Turn off the mains water supply va lve at the appliance. See
Figs . 21 and 28. Thi s is operated using a flat blade screwdriver.
Later versions of
th e water flow regulator have a drain screw
which
must be loosened to remove more water. See Fig. 41 .
A
quantity of water will remain in th e Wa ter to Water heat
exchanger and extra care mu st be taken when removing this
component.
23
14 . 4. COMPONENT REPLACEMENT.
1. Central Heating Sensor. See Fi g 32 .
Ch eck th at the electrical supply has been turned off.
Rem o ve the inner casing cover. See Section 13.3 (c)
Drain the he at in g circuit as described in Secti on 14.3 (a ).
Ca refu ll y pull off the two leads from the sensor and unscrew th e
sensor from
th e heat exchanger.
Fi t the replacement sensor with the washer. Refi t the leads.
Open the
va lves. Fill and repressuri se the syst em as described in
Section 11 .2.
2. Automatic Air Vent.
See Fig . 32.
Remove
the inner casing cover. See Section 13.3 (c) .
Drain
the heating circuit as described in Section 14.3 (a).
Remove
the central hea ting sensor connector.
Unscrew
the assembl y. Fit the repl acement as sembl y in the re-
verse order. Re fi t the sensor connection.
Op en the va lves, fill and re pr essuri se the system as described in
Section 11 .2.
3. Fan.
See Figs. 15 and 18.
Check that the electrical supply has been turned off.
Remove
the fan as describ ed in Se ct i on 13.3 ( e). Fit the replace-
ment fan ass embly in the reverse order.
4. Air Flow Pressure
Sw it ch . See Figs . 15 and 33 .
Ch eck th at th e electrical supply has been tu rned off.
Rem ove the inner cas in g cover. See Section 13.3. ( c) .
Pull off the suction tu bes from the switch. Se e Fig . 15 . Carefully
pull off the el ectrical connections fr om the switch. Unscrew the
sc rews and remove the switch from the bracket.
Fit the replacement switch in
the reverse orde r.
Check that the electrical connections have been made to the cor-
rect terminals on the switch. See Fig . 33 .
5. Overheat Thermostat. See Figs. 22 and 34
Ch eck that the electrical su pp ly has been turned off.
Rem ove the inner casing cover. See Section 13.3. (c).
Unscrew the two screws fixing the top panel. Lift the panel an d
push backwards to release the lugs. Remove the panel. Se e Fig . 22 .
Rem ove the cl ip and pu ll the thermostat phial from the pocket.
See Fi g. 34 . Carefully pull off the leads from the terminals on th e
thermostat head . Unscrew the nut fixing the thermo stat head .
Remove
the the r mostat from the inner casing.
Fit a new thermostat in the reverse order.
Fig. 32. Central heating sensor.
Fl ue hood fixi ng ho ok

Worcester 350 Combi Specifications

General

Brand	Worcester
Model	350 Combi
Category	Boiler
Language	English