Benchmark Alpha E-Tec Plus 28 Installation And Servicing Instruction page 40

7.3 PREPARE FOR SERVICING - Fig. 7.5
1. Ensure the electrical supply is isolated and the gas supply is off.
2. Gain access by removing the control panel cover, case front panel and lowering the control panel as described in
Section 7.2.
3. Remove the condensate trap assembly and clean as described in Section 8.11.
4. Remove the single screw securing the top of the air supply pipe and withdraw it from the fan connection.
5. Pull off the ignition lead from the electrode.
6. Remove the upper and lower spring clips from the gas supply pipe.
7. Remove the gas valve pressure tube from the fan inlet
8. Disconnect the fan wiring connector.
9. Remove the four 10 mm nuts securing the combustion chamber front assembly. See Fig. 7.6.
10. Withdraw the complete burner/fan/air inlet assembly towards you.
Front panel insulation
Combustion chamber
front assembly
Insulation panel
clips (3 off)
7.4 CLEANING THE ELECTRODES, BURNER AND FAN
1. Check the condition of the burner. Clean carefully using a vacuum or compressed air.
2. Check the condition and gap of the electrodes.
If they are in good condition, remove any oxide deposits using a fine abrasive paper.
If it is necessary to replace the electrode assembly, ensure a new gasket is used.
3. Check that the fan is clean and rotates freely. Carefully clean the impellor with a soft bristle brush if necessary
7.5 CLEANING THE HEAT EXCHANGER (with the condensate trap in place)
1. Remove any deposits from the heat exchanger coils using a suitable non metallic soft brush, then a vacuum cleaner
or water sprayed onto the coils. Ensure all electrical components are protected from water (if used). Any water used to
clean the heat exchanger will drain to the condensate trap.
2. Check the condition of the combustion chamber insulation panels. Any damaged panels must be replaced.
3. Check the condition of the burner injector in the gas valve outlet, carefully clean with a soft brush if necessary - Do not
use a brush with metallic bristles as this might damage the injector. Unscrew and replace the injector should it appear
damaged.
40
Alpha E-Tec Plus 28, 33 and 38 - Routine Servicing
Burner
Electrode to burner gap
7 mm ± 1 mm (28, 33 models)
5.5 mm ± 1 mm (38 model)
Ignition/ sensing electrodes
Fig. 7.5
Spark gap between
electrodes 3.5 mm ± 0.5 mm