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REPLACEMENT PARTS
Product Name
6 720 ... ... (YYYY/MM)
11.1.6 Primary Heat Exchanger
Electrode assembly:
▶ Switch off the master switch.
▶ Isolate the appliance from the power supply.
▶ Move the control panel into the service position, refer to
section 10.4.1.
▶ Release the four screws to remove the inner case door.
▶ Remove the leads from the electrodes.
▶ Unscrew the two fixing screws [2] and remove the electrode
assembly [1], that includes the gasket [3] and heatshield [4].
▶ Replace and re-connect the assembly taking care not to mislay the
inspection window.
▶ After re-assembly check that the CO/CO
2
levels as described in the
section “Setting the air/gas ratio”.
Burner:
▶ Check that the gas cock is turned off and the master switch is in the
OFF position.
▶ Isolate the appliance from the power supply.
▶ Remove the clips, castellated nuts and springs [5] from the studs
[6].
▶ Unscrew and remove the two hexagon screws [7] securing the fan.
▶ Remove nut and washer [8] from the rear stud [9].
▶ Remove the burner cover plate [10].
▶ Remove the burner [11].
▶ Re-assemble the new burner in reverse order.
▶ Replace the burner seal [12] with a new one.
▶ Refer to the section “Re - assembly of the burner cover” on page 42.
▶ After re-assembly check that the CO/CO
2
levels as described in the
section “Setting the air/gas ratio”
Primary heat exchanger:
▶ Isolate the appliance from the power supply.
▶ Turn off all the isolation valves.
▶ Drain down the appliance.
▶ Move the control panel into the service position, refer to
section 10.4.1.
▶ Remove the inner case door.
▶ Remove the fan assembly, gas mixing tube, refer to section 11.1.2.
▶ Disconnect and remove the sensors connected to heat exchanger,
refer to section 11.1.3.
▶ Remove the condensate trap, refer to section 11.1.4.
▶ Remove the internal flue elbow [13] and tube from the boiler sump.
▶ Disconnect the return pipe union clip [14] at the base of the boiler
heat exchanger and disconnect the pipe.
▶ Remove the plastic nut [15] from the base of the inner casing.
▶ Disconnect the flow pipe [16] at the union on the heat exchanger.
▶ Remove the heat exchanger from the inner casing.
▶ Ensure that heat conductive paste is used on the sensors when
refitting.
▶ Check the seals and replace if necessary.
▶ After re-assembly check that the CO/CO
2
levels are as described in
the section “Setting the air/gas ratio”.
Fig. 72 Primary heat exchanger
Fig. 73 Primary heat exchanger removal
WARNING:
Burner
▶ Do not remove the burner unless a new gasket is
available for re-assembly.
4
6
9
2
11
12
10
5
7
3
1
14
15
13
16
8
6720809859-40.1W
o
14
15
6720809859-41.1W
o