Worcester WR325 RSF Installation And Servicing Instructions page 16

14.3 Heat exchanger
Check that the electricity supply is turned off. Remove the fan
as described in 13.3 (b). Unscrew the two screws and remove
the cross-piece at the top. Isolate from the incoming cold water
supply and drain down the heater. Disconnect the inlet and outlet
pipes outside the base of the combustion chamber. remove the
retaining screw inside the heat exchanger and remove from the
heater. Fit the replacement heat exchanger in the reverse order.
14.4 Burner
Remove the burner as described in 13.3 (c). Fit the replacement
burner in the reverse order ensuring that it is located correctly.
14.5 Electrodes
Remove the burner as described in 13.3 (c). slacken the
clamping screw and slide the electrode upwards. Fit the
replacement burner in the reverse order ensuring that it is located
correctly.
14.6 Injectors
Remove the burner as described in 13.3 (c). Remove the burner
manifold to expose the injectors. The injectors can then be
removed and replaced as required. Fit the replacement burner
in the reverse order ensuring that it is located correctly.
14.7 Micro-switch
Slacken the three screws from underneath and release the
housing from the valve body. *Unscrew the three screws and
remove the black plastic cover. Remove the spade terminals
form the microswitch. Replace the switch in the reverse order
and check the adjustment as follows;
Turn all hot water taps off.
Remove the small black plastic cover from underneath the
switch.
With the electricity on, turn the screw anti-clockwise until the
fan starts.
Turn the screw clockwise 1½ times to reset the switch.
This adjustment must be carried out whenever any of the water
valve components have been disturbed.
14.8 Water valve
Remove the micro-switch as described in 14.7. Drain the water
circuit. Disconnect the inlet connection at the rear of the valve.
Pull out the retaining clip at the right hand side of the valve.
Slacken the two screws at the base of the gas valve and lower
the water valve. Fit the venturi to the new valve. Fit the replace-
ment valve in the reverse order ensuring that both the face to
face joint and o-ring seal are correctly positioned.
14.9 Gas valve
Remove the water valve as described in 14.8. unplug the elec-
trical connections from the solenoid. Undo the inlet connection
at the rear of the valve. Undo the union connection inside the
combustion chamber and remove the valve. Fit the replace-
ment valve in the reverse order ensuring that the seals are cor-
rectly positioned and gas tight. Re-commision the heater as
described in section 11.
14.10 Air pressure switch
Carefully pull off the sensing tubes from the switch noting the
position of the coloured tubes. Unscew the screw from inside
the combustion chamber and remove the switch. Remove the
two screws and remove the cover to expose the spade termi-
nals. Fit the replacement switch in the reverse order ensuring
that the tubes are correctly fitted.
14.11 Internal fuses
Undo the screw and remove the control box housing from the
heater. Remove the four screws and remove the cover. Remove,
check and replace the fuses if required. Re-assemble in the
reverse order.
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14.12 Control board
Remove the control box and cover as described in 14.11. Care-
fully unplug the two multi-way plugs and the ignition lead termi-
nals. Disconnect the mains connections from the terminal and
pull away the locking clamp. Carefully release the control board
from the plastic clips and remove. Fit the new control board in
reverse order.