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Replace any components removed from the appliance in the
reverse order using new gaskets/O-rings/sealant where
necessary. Always check that any electrical connections are
correctly made and that all screws are tight.
Remove casing and cover panels and lower the facia, as
necessary, to gain access to the controls. Refer to Clause
14.3.1.1-7.
15.4.1. Gas valve
Disconnect or unplug the electrical connections at the valve.
Remove the bottom panel. Unscrew the four flange screws at the
top and the union connection at the bottom manifold and
remove the assembly. Use the new O-rings provided when fitting
the new valve. Refer to Fig 40.
Set the gas valve:
1. Connect a pressure gauge to the burner pressure test point on
the gas valve. Refer to Fig. 40.
2. Switch on the gas and electrical supplies. Check for gas
tightness at the gas valve inlet.
3. Carefully pull off a connection from the Modureg adjuster on
the gas valve. Fully open a hot water tap. The burner will light
and operate at the minimum pressure.
4. Remove the cap from the Modureg.
5.Adjust the 9mm nut to give the minimum pressure appropriate
to the gas, clockwise to increase and counter clockwise to
decrease the pressure. 1.5mbar for natural gas (G20) or 6mbar
for propane (G31). Refer to Fig. 46.
Fig 46-Burner Pressure Adjuster (Modureg)
3
2
4
5
1
6. Push the shaft on the Modureg down to the stop and hold it
there. The burner pressure will increase. Adjust the 7mm nut to
set the maximum pressure appropriate to the gas, 14.2mbar for
natural gas (G20) or 34.7mbar for propane (G31). Note: If there is
any difficulty in achieving these pressures then check the inlet
pressure at the gas valve. Refer to Section 9.3.
7. Turn off the hot water tap.
8. Replace the Modureg cap and screw it in place. Refit the
electrical connection to the Modureg.
9. Run the appliance in each mode to check the setting
pressures. Central heating, 8.3mbar for natural gas (G20) or
19.2mbar for propane (G31). Refer to Section 15.4.12 if
necessary, to set the central heating pressure.
10. Switch off the appliance and disconnect the pressure gauge.
11. Relight the appliance and check for gas soundness.
15.4.2. Spark Electrode
Remove the inner casing cover.
1. Modureg
2. Cap
6
3. Shaft
7
4. Maximum Pressure
Adjuster
5. Minimum Pressure
8
Adjuster
6. Cap Fixing Screw
7. O-Ring
8. Connections
Carefully pull off the leads at the electrode assembly. Unscrew
the two screws and remove the spark electrode assembly from
the burner. Refer to Fig 43.
15.4.3. Flame Sensing Electrode
Remove the inner casing cover.
Separate the electrode lead in-line connector. Release the locknut
on the support bracket and remove the sensing electrode from
the burner. Refer to Fig 44.
15.4.4. Burner and Manifold
Remove the electrodes.
Remove the burner support brackets.
Remove the combustion chamber cover. Unscrew the two blade
assembly fixing screws and loosen the two locating screws. Lift
the blade assembly from the manifold. Remove the two
extended screws and lift out the manifold assembly. Do not omit
the O-ring when fitting the new burner. Refer to Fig 45.
15.4.5. Combustion Chamber Insulation
Remove the combustion chamber cover.
Slide out the side insulation pads and then lift out the rear pad.
Fit new insulation pads in the reverse order. Remove and replace
the pad from the combustion chamber front cover. Refer to
Fig 47. To avoid the risk of fine particles dampen the pads before
removal.
15.4 6. Pressure Gauge
Drain the primary system. Refer to 15.3.1. Lower the facia and
unclip the gauge. Pull out the clip from the manifold and remove
the capillary. Refill and pressurise as described in Section 12.4-8 -
Commissioning. Refer to Fig 27 and 48.
15.4.7. Relief valve
Drain the primary system. Refer to 15.3.1. Lower the facia.
Disconnect the relief valve drain pipe. Undo the union
connection and remove the relief valve. Refill and pressurise as
described in Section 11 - Commissioning. Refer to Fig 27.
Fig 47-Combustion Chamber Insulation
1
3
1. Flue Hood Clamp Location Slots
2. Combustion Chamber Casing
3. Side Insulation Pads
4. Rear Insulation Pad
15.4.8. Flow Regulator
Drain the hot water circuit. Refer to 15.3.2. Lower the facia.
Disconnect and remove the inlet water pipe between the DHW
heat exchanger and flow switch. Remove the regulator. Ensure
that new regulator is correctly aligned. Refer to Fig 49.
15.4.9. Inlet Water Filter
Drain the hot water circuit. Refer to 15.3.2. Remove the bottom
panel. Lower the facia.
Disconnect the inlet water pipe at the manifold and the flow
switch. Remove the filter. Ensure that the new filter is correctly
aligned. Refer to Fig 49.
21
2
3
4
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