Worcester 26CDi Xtra, Installation And Servicing Instructions

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2. Air Flow Pressure Switch. See fig.34.
Check that the electricity supply to the appliance is turned off.
Remove the cabinet front panel and hinge the facia down into
the Service Position, as described in Sections 13.3 (a) and
13.3 (c).
Note the position of the tubes and electrical connections.
Carefully pull off the sensing tubes and the electrical connections
from the switch.
Undo the two screws located under the gas valve and remove
the switch with the support bracket from the appliance. Remove
the support bracket, held by two screws, from the switch. Retain
the screws and bracket discard the switch.
Fit the replacement switch in the reverse order ensure the
electrical connections are made to the correct terminals. Connect
the red sensing tube to the position marked ‘+’ positive and
clear tube to the position marked ‘–’ negative.
Reassemble the appliance in the reverse order.
3. Fan. See fig. 32.
Check the electricity supply to the appliance is turned off.
Remove the fan assembly as described in Section 13.3(e) and
discard.
Fit the replacement fan in the reverse order.
Refer to Section 13.3 (e) when replacing the fan, fitting the
sensing tubes and making the electrical connections.
Reassemble the appliance in the reverse order.
4. Overheat Thermostat. See fig. 33.
Check that the electricity supply to the appliance is turned off.
Remove the inner casing cover as described in Section 13.3 (b).
Carefully pull off the two wires from the thermostat head.
Remove the two M3 screws fixing the thermostat to the
mounting plate on the heat exchanger. Retain the screws and
discard the thermostat.
Fit the replacement thermostat in the reverse order ensure some
heat sink compound is between the thermostat and the
mounting plate.
Reassemble the appliance in the reverse order.
5. Gas to Water Heat Exchanger. See figs. 32 and 33.
Check that the electricity supply to the appliance is turned off.
Drain the central heating circuit as described in Section 14.2 (a).
Remove the inner casing cover, fan, flue hood assembly, overheat
thermostat, central heating sensor and burner as described in
Section 13.3 (b, e, f, g and h) and Section 14.3 (4) and (12).
Slacken the two screws and remove the two side retaining
brackets. Lift the heat exchanger clear of the casing.
Take care the rear insulation panel does not drop forwards onto
the burner.
Retain the screws and brackets discard the heat exchanger.
Fit the replacement heat exchanger in the reverse order. Ensure
both ‘O’ rings are correctly fitted and lubricated.
Apply a layer of heat sink compound to each of the thermostats.
Open the valves and fill and re-pressurise the system as
described in Section 11.1.
Reassemble the appliance in the reverse order.
6. Combustion Chamber Insulation. See figs. 32 and 35.
Check that the electricity supply to the appliance is turned off.
Drain the central heating circuit as described in Section 14.2 (a).
Remove the inner casing cover, fan assembly, flue hood
assembly, combustion chamber front and sides assembly and
gas to water heat exchanger as described in Sections 13.3 (b, e, f
and g), and 14.3 (5).
Remove the fibre insulation pads from the combustion chamber
sides, rear, and front sections. To avoid the risk of fine particals
dampen the pads before removal.
Discard the insulation pads.
Fit the replacement pads in the reverse order. Take care not to
damage the pads
Reassemble the appliance in the reverse order.
Open the valves and fill and re-pressurise the system as
described in Section 11.1.
7 . Burner. See figs. 32 and 36.
Check that the electricity and gas supplies to the appliance are
turned off.
Remove the burner assembly as described in Section 13.3 (h)
and discard.
Fit the replacement burner and reassemble in the reverse order
taking care not to damage the electrode leads.
When reassembling the appliance follow the description in
Section 13.3 (h).
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Fig. 33. Gas to Water Heat Exchanger
and Auto Air Vent.
Auto air vent
Gas to water
heat exchanger
Retaining
clips
C.H.
sensor
Retaining
screws (2)
Retaining
screws (2)
Overheat
thermostat
Retaining
bracket (2)
Fig. 34. Air Flow Pressure.
Gas valve
Fixing screws (2)
Sensing tube
Fixing screws (2)
Support bracket