Alpha CD12S - Page 33

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Alpha CD12S/20S/28S - Component Replacement
8.19 PRIMARY TEMPERATURE SENSOR - Figs. 32, 34
1. Gain access as described in Section 8.1 and drain the heating circuit as described in Section 8.2.
2. The primary temperature sensor is positioned on the bottom left hand side of the heat exchanger flow pipe, see Fig. 31.
Disconnect the wiring and unscrew the sensor. Re-assemble in reverse order with a new sensor and sealing washer.
8.20 AUTOMATIC AIR VENT - Fig. 32
1. Gain access behind the front casing and drain the boiler heating circuit as described in Sections 8.1 and 8.2.
2. Remove the retaining clip from the manifold and lift out the automatic air vent. Fit a new one using a new 'O' ring.
3. Refill and pressurise the system. (Refer to Commissioning, Section 5.1).
8.21 PUMP - Refer to Fig. 32
Gain access behind the front casing and drain the boiler heating circuit as described in Sections 8.1 and 8.2.
Pump head
1. Using a 5 mm Allen key remove the four socket head screws securing the pump head to the body. Withdraw the head,
remove the wiring cover and disconnect the plug.
2. Connect the plug to the new head. Ensure the pump is set to maximum (3) and re-assemble in reverse order.
3. Refill and pressurise the system. (Refer to Commissioning, Section 5.1).
8.22 PRIMARY PRESSURE SWITCH - Fig. 32
1. Gain access behind the front casing and drain the boiler heating circuit as described in Sections 8.1 and 8.2.
2. Disconnect the wiring from the pressure switch.
3. Unscrew the switch from the primary flow pipe.
4. Using the new washer supplied, re-assemble in reverse order.
When connecting the wiring to the new switch the polarity of the wires is not important.
8.23 PRESSURE RELIEF VALVE - Fig. 32
1. Gain access behind the front casing and drain the boiler heating circuit as described in Sections 8.1 and 8.2.
2. Disconnect the pressure relief valve outlet fitting.
3. Remove the four screws at the bottom of the boiler, either side of the flow and return connections and the two screws
securing the expansion relief valve.
4. Lift the pump assembly and pull the pressure relief valve to disconnect it from the pump housing.
5. Re-assemble in reverse order.
6. Refill and pressurise the system. (Refer to Commissioning, Section 5.1).
8.24 EXPANSION VESSEL - Fig. 31
1. Gain access behind the front casing and drain the boiler heating circuit as described in Sections 8.1 and 8.2.
2. Disconnect the pipe from the expansion vessel.
3. Remove the screw securing the top support bracket.
4. Lift the expansion vessel out of the boiler.
5. When replacing the vessel, ensure that the connection is towards the left of the boiler and re-assemble in reverse order
using new seals as necessary.
6. Refill and pressurise the system. (Refer to Commissioning, Section 5.1).
8.25 CYCLONE (if wall jig is fitted) - Fig. 14b
1. Remove the bottom tray and close the isolating valves either side of the cyclone.
2. Disconnect the unions from the cyclone. Remove the two screws securing the support bracket and remove the cyclone.
Re-assemble with a new cyclone.
3. Pressurise the system. (Refer to Commissioning, Section 5.1).