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REPLACEMENT OF PARTS - PAGE 35
9. 13 TO REPLACE THE HEAT EXCHANGER
Ensure that the system is drained.
1.
Remove the case and completely dismantle the boiler as described in sections 7.1 and 7.2.
2.
Drain the system.
Note: When the system is drained, filled or vented, the manual lever on the right hand side of the diverter valve,
see Fig. 27, must be moved to the 'MAN OPEN' (top) position. Return it to its original position after the system has
been filled and vented.
3.
Remove the two screws securing the overheat cut-off device to the heat exchanger.
4.
Undo the two tubing nuts at the bottom of the heat exchanger and remove it from the boiler - lift it up slightly to
disengage the pipes and to clear the combustion chamber then withdraw it forwards.
5.
Fit the new heat exchanger. Replace the overheat cut-off device and secure in position with the two screws previously
removed.
6.
Fill the system and vent the boiler as described in section 3.16, paragraphs 2 to 5. Check the heat exchanger
connections for water soundness.
7.
Reassemble the boiler as described in section 7.4.
8.
Refer to the Lighting Instructions, section 8 and light the boiler.
9.14 TO REPLACE THE PUMP OVERRUN THERMOSTAT
The pump overrun thermostat is situated on the base of the chassis, just to the right and above the control box.
1.
Gain general access as described in section 9.1, paragraph 1.
2.
Remove the screw securing the control box, see Fig. 25 and lower the control box.
3.
Disconnect the three wires and remove the two screws securing the thermostat to the chassis.
4.
Fit the new thermostat and secure with two screws.
5.
Connect the wires to the thermostat - red to terminal 1, yellow to terminal 2 and brown to terminal 3.
6.
Reassemble the boiler as described in section 9.2, paragraphs 5 to 9.
7.
Refer to the Lighting Instructions, section 8 and light the boiler.
Allow the boiler to heat up fully then switch it off at the programmer or external controls and check that the pump
continues to run for 5 to 15 minutes.
9. 15 TO REPLACE THE GAS VALVE
Refer to Fig. 39.
1.
Gain general access as described in section 9.1,
paragraph 1.
2.
Disconnect the gas valve electrical plug from the valve.
3.
Disconnect the pilot supply from the top of the gas valve.
4.
Remove the four 3 mm socket screws securing the gas
valve to the burner manifold.
5.
Remove the screw securing the inlet manifold to the side
of the chassis.
6.
Undo and disconnect the union at the gas service cock
and withdraw the gas valve.
Remove and discard the 'O' ring in the burner manifold.
7.
Remove the four 3 mm socket screws securing the inlet
manifold and fit it to the new valve, using a new 'O' ring
(both 'O' rings are the same).
8.
With a new 'O' ring in the burner manifold secure the new valve to the manifold using the four socket screws previously
removed.
9.
Reconnect the pilot supply, gas service cock union, plug and secure the inlet manifold to the chassis.
10. Open the gas service cock and test the union and inlet manifold to gas valve connection for gas soundness.
11. Refer to the Commissioning Instructions, section 4.3, paragraph 4. Light the boiler and test the pilot supply and burner
manifold connections at the gas valve for gas soundness.
12. Reassemble the boiler as described in section 9.2, paragraphs 7 to 9.
35
REPLACEMENT OF PARTS
Supplied By www.heating spares.co Tel. 0161 620 6677
Fig. 39
Manual No. 405/0101
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