Alpha CD25C Installation And Servicing Instructions page 28

8.17 PRIMARY HEAT EXCHANGER - See Fig. 31
1. Gain access behind the room sealed chamber panel as described
in Section 8.1 and drain the boiler heating circuit as described in
Section 8.2.
2. Disconnect the gas inlet union from the combustion chamber front.
3. Remove the two screws and six nuts and washers securing the
combustion chamber front burner assembly and remove.
4. Remove the overheat thermostat (Section 8.9), flue thermostat
(Section 8.10) and the primary temperature sensor (Section 8.20).
5. Disconnect the condensate drain union by pulling out the clip.
6. Undo the two nuts from the heat exchanger flow and return pipes.
7. Remove the four screws securing the heat exchanger retaining
brackets. Two on the front left and two at the rear to the right.
8. Lift up the heat exchanger off the pipes and remove it by carefully
withdrawing it out of the boiler.
9. Re-assemble in reverse order, ensuring that new seals are used.
Lubricating the seals with the grease supplied will aid assembly.
10. Refill and pressurise the system. (Refer to Commissioning,
Section 5.1).
8.18 COMBUSTION CHAMBER INSULATION
Gain access to the combustion chamber as described in Section 8.1.
Front insulation - see Fig. 27
1. Remove the electrodes from the combustion chamber front as described in Section 8.3.
2. Remove the four screws securing the burner.
3. Carefully remove the insulation.
Back insulation - see Fig. 31
1. Remove the combustion chamber front/burner assembly.
2. Remove the centre screw retaining the insulation.
3. Carefully remove the insulation, suction applied to the centre of the insulation will aid this.
Fit a new panel and re-assemble in reverse order.
Refill and pressurise the system. (Refer to Commissioning, Section 5.1).
8.19 PRESSURE GAUGE - Fig. 32
1. Gain access behind the casing and drain the boiler heating circuit as described in Sections 8.1 and 8.2.
2. Remove the circlip securing the pressure gauge sensor and withdraw the sensor.
3. Remove the main cable grommet in the bottom panel and remove the sensor tube.
4. Depress the two lugs on the pressure gauge and push it out of the control panel.
5. Fit the new gauge using a new 'O' ring on the manifold connection if necessary.
6. Refill and pressurise the system. (Refer to Commissioning, Section 5.1).
DHW sensor
Alpha CD25C/28C/35C - Component Replacement
28
Back insulation panel
Two screws securing
heat exchanger
Fig. 32
Two screws
securing heat
exchanger
Fig. 31
Primary pressure switch
Automatic air vent
Pump
Diverter valve
Pressure relief valve
Pressure gauge