6.9.15 Gas Valve; 6.9.16 Electrode Assembly And Heatshield; 6.9.17 Burner; 6.9.18 Primary Heat Exchanger - Worcester Greenstar Highflow 440CDi ERP Installation, Commissioning And Servicing Instructions

6.9.15 Gas valve

▶ Check that the gas cock is turned off.
▶ Disconnect the black rubber tube [1] from the gas valve.
▶ Remove the solenoid connections [2] at the side of the gas valve.
▶ Release the gas inlet union [3] at the inlet.
▶ Undo the union [4], within the inner casing, securing the valve to the
gas/air tube.
▶ Transfer the inlet pipe assembly to the new gas valve.
▶ Reconnect the plastic union [4] to the gas valve.
▶ Reconnect the solenoid connection [2].
▶ Re-attach the black rubber tube [1] to the gas valve
▶ Check for gas tightness when the new gas valve has been fitted.
▶ After re-assembly check CO/CO
"Setting the air/gas ratio" on page 36.
1
2
Fig. 67 Gas valve

6.9.16 Electrode assembly and heatshield

WARNING: Electrode assembly
▶ Do not remove the electrode assembly unless a new
gasket is available for re-assembly.
▶ Switch off the master switch.
▶ Isolate the appliance from the power supply.
▶ Move the control panel and expansion vessel into the service
position.
▶ Release the 4 screws to remove the inner case door.
▶ Remove the leads from the electrodes.
▶ Unscrew the two fixing screws [2] and carefully remove the
electrode assembly [1].
▶ Inspect the spark/flame electrode assembly and ceramics for signs of
contamination or damage, replace as necessary.
▶ Re-assemble the electrode set with a new gasket and secure with the
screws [2] removed earlier.
▶ After re-assembly check that the CO/CO
section "Setting the air/gas ratio" on page 36.
6720818077 (2016/04) -
Greenstar Highflow CDi
levels as described in the section
2
4
3
levels as described in the
2
ErP

6.9.17 Burner

WARNING: Burner
▶ Do not remove the burner unless a new gasket is
available for re-assembly.
▶ Turn the gas cock and the master switch to their OFF positions.
▶ Isolate the appliance from the power supply.
▶ Remove the clips [3a], castellated nuts [3b] and springs [3c] from
the studs [3].
▶ Remove the nut [4a] from the rear stud [4].
▶ Disconnect the mixer unit from the fan.
▶ Remove the connector and earth wire from the fan.
▶ Remove the burner cover plate [5] and fan assembly [6].
▶ Remove the burner [7].
▶ Re-assemble the new burner in reverse order.
▶ Replace the burner seal [8] with a new one.
▶ Refer to the section "Re-assembly of the burner cover" on page 36.
▶ After re-assembly check that the CO/CO
section "Setting the air/gas ratio" on page 36

6.9.18 Primary heat exchanger:

▶ Isolate the appliance from the power supply.
▶ Turn off all the isolation valves.
▶ Drain down the appliance.
▶ Move the control panel and the expansion vessel into the service
position.
▶ Remove the inner case door.
▶ Remove the fan assembly, burner, and gas mixing unit.
▶ Disconnect and remove the sensors connected to heat exchanger.
▶ Remove the condensate trap.
▶ Remove the internal flue elbow and tube from the boiler sump.
▶ Release the return pipe union [10] at the base of the heat exchanger.
▶ Remove the plastic nut [11] from the base of the inner casing.
▶ Release the retaining bracket [9] from the inner chassis
▶ Remove the heat exchanger from inner casing.
▶ Ensure that heat conductive paste is used on sensors when refitting.
▶ Check the seals and replace if necessary.
▶ After re-assembly check that the CO/CO
the section "Setting the air/gas ratio" on page 36.
6
3b
3c
1
3
2
Fig. 68 Primary heat exchanger
SERVICING AND SPARES
levels as described in the
2
levels are as described in
2
3a 4a
5
7
9
4
8
10
11
41