Alpha InTec2 20SE Installation And Servicing Instruction page 41

7.8 PCB - Fig. 7.2
Note: The replacement of the gas valve or PCB must be carried out by a Gas Safe registered engineer with the use of a flue
analyser.
Gain access as described in Section 7.1.
1. Unhook the ignition lead from the rear of the control panel, release the grommet and unplug the lead from the PCB.
2. Remove the three retaining screws in the PCB cover and remove cover. See Fig. 7.2.
3. Remove the PCB retaining screws.
4. Release the retaining clips, lift the PCB from the control panel and unplug the wire connections.
5. To maintain the boiler parameter setting, remove the memory chip from the removed PCB and insert into the new PCB.
6. Re-assemble in reverse order. Refer to the wiring diagram in Section 8.1 for connections.
When replacing the cover, ensure no wires are trapped and all wiring is secured. Secure with three screws - do not over
tighten.
7. Test the boiler and carry out the fast calibration as described in Section 5.13.
Note; If the original PCB memory chip is not used in the new PCB the boiler parameters will need to be set and full
calibration procedure is required.
7.9 PRESSURE GAUGE - Fig. 7.2
Gain access to the boiler as described in Sections 7.1 and 7.2.
1. Withdraw the retaining clip securing the pressure gauge sensor (just to the left of the automatic air vent) and withdraw
the sensor.
2. Remove the main cable grommet in the bottom panel and remove the sensor tube.
5. Depress the two lugs on the pressure gauge and pull it out of the control panel.
4. Fit the new gauge using a new 'O' ring on the connection if necessary.
5. Refill and pressurise the system. (Refer to Commissioning, Section 5.1).
7.10 GAS VALVE – BURNER INJECTOR
Note: The replacement of the gas valve or PCB must be carried out by a Gas Safe registered engineer with the use of a flue
analyser.
Isolate the boiler gas supply and gain access as described in Section 7.1.
1. Disconnect the electrical plug from the gas valve.
2. Remove the gas pipe retaining clip from the top of the gas valve and remove the pipe.
3. Disconnect the gas valve union beneath the boiler.
4. Remove the two screws from beneath the boiler and lift out the valve assembly.
5. Unscrew the injector from the top of the gas valve and transfer the injector to the new gas valve using a new washer.
6. Fit the new assembly and re-assemble in reverse order and test for gas tightness.
7. Light the boiler. (Refer to Commissioning, Section 5.4).
8. Test the boiler and carry out the fast calibration as described in Section 5.13.
7.11 PRIMARY FLOW/RETURN TEMPERATURE SENSOR and OVERHEAT THERMOSTAT - Fig. 7.1
Gain access to the boiler as described in Section 7.1.
1. Unplug the wiring and unscrew the sensor using a 13 mm spanner.
2. Re-assemble in reverse order with a new sensor. Do not overtighten.
7.12 AUTOMATIC AIR VENT - Fig. 7.1
Gain access and drain the boiler heating circuit as described in Sections 7.1 and 7.2.
1. Turn the automatic air vent anticlockwise and lift it out.
2. Insert the new air vent using a new washer and turn it clockwise to lock it in position.
3. Refill and pressurise the system. (Refer to Commissioning, Section 5.1).
Alpha InTec² 20SE and 30SE - Component Replacement
41