26
It is the law that any service work must be carried out by a competent person, i.e. CORGI registered personnel.
Warning: Before replacing any boiler components, set the selector switch to 0, isolate the electrical supply and close the boiler
gas service cock. Allow the boiler to cool.
Always test for gas soundness after replacing any gas carrying components or disturbing any gas connections.
Check the operation of the boiler. (Refer to Boiler Operation, Section 6). Ensure that all the controls are returned to their original settings.
The replacement of components in Sections 8.3 to 8.17 does not require draining of the boiler.
8.1 GENERAL ACCESS - Fig. 27
Ensure the electrical supply is isolated and the gas supply is off.
Remove the two screws securing the bottom of the front casing. Pull the bottom forwards, then upwards and remove the casing.
1. If access is required behind the control panel - Remove the two fixing screws (one each side) securing the control
panel and hinge it forward.
2. To gain access to the combustion chamber - Remove the front casing top bracket by removing the six screws securing
it to both side panels and the room sealed chamber. Remove the two bottom screws securing the left hand side panel, lift
the panel up slightly and remove. Remove the three screws and release the two clips securing the room sealed chamber
panel and remove the panel, taking care not to damage the seal. When replacing the panel, ensure the seal is intact and
in position.
3. To gain access to the control panel components - Remove the five screws securing the rear cover and carefully raise
the cover from the front. When replacing the cover, ensure no wires are trapped and all wiring grommets are in position.
Secure with five screws - do not overtighten.
8.2 DRAINING THE BOILER - Refer to Fig. 15
Set the selector switch to 0, isolate the electrical supply and close the boiler gas service cock (see Fig. 15). Allow the boiler to cool.
Remove the two screws securing the bottom of the front casing. Pull the bottom forwards and remove. Remove the two fixing
screws (one each side) securing the control panel and hinge it forward.
1. Heating circuit (refer to Fig. 15)
Close the central heating flow and return valves and drain the heating circuit via the drain point (G in Fig. 15).
2. Hot water circuit (refer to Fig. 15)
Close the mains water supply valve and drain the hot water storage cylinder via the store drain tap (I in Fig. 15). Open any
hot tap below the level of the boiler to allow as much draining as possible.
Note: Some water will remain in the components and care must be taken when removing them.
8.3 ELECTRODES - Refer to Fig. 28
Gain access behind the room sealed chamber panel as in Section 8.1.
1. Ignition electrode and lead
Disconnect the lead from the ignition generator, noting its position.
Remove the two screws securing the electrode to the front of the combustion chamber and carefully withdraw the electrode.
2. Flame sensing electrode and lead
Remove the grommet in the bottom of the chamber, disconnect the flame sensing electrode in-line connector and
withdraw the lead.
Remove the two screws securing the electrode to the front of the combustion chamber and carefully withdraw the electrode.
3. Ignition electrode
Remove the two screws securing the electrode to the front of the combustion chamber and carefully withdraw the electrode.
Re-assemble in reverse order
8.4 MAIN BURNER - Refer to Fig. 28
1. Remove the burner assembly as described in Routine Servicing, Section 7.2.
2. Remove the four screws securing the burner to the combustion chamber front assembly.
3. Re-assemble with a new burner as described in Routine Servicing, Section 7.4.
8.5 BURNER INJECTOR - Refer to Fig. 27
1. Gain access behind the room sealed chamber panel as described in Section 8.1.
2. Undo the gas inlet union to the combustion chamber front to gain access.
3. Unscrew the damaged injector and screw in a replacement.
4. Re-assemble in reverse order.
Alpha CD50 - Component Replacement
8 COMPONENT REPLACEMENT
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