IMPORTANT: Turn off the gas supply and electrically isolate
the appliance before replacing any components
.
After the replacement of any components always check for gas
soundness where relevant and carry out functional checks as
described in Section 12-Commissioning.
Any O-ring or gasket that appears damaged must be replaced.
Complete gasket and O-ring packs are available for gas and
water connections on the appliance.
Component Access
Refer to Section 14, Inspection and Servicing for access to
components.
Draining the Appliance
Primary System: Turn off the heating flow and return valves at
the appliance. Refer to Fig 17.
Open the drain tap a short tube is already connected to the drain
point. Refer to Fig. 20. Close the drain tap when the flow from the
appliance has stopped.
DHW Circuit:
Turn off the mains cold water supply at the
appliance. Refer to Fig 16. Open a hot tap below the level of the
appliance to drain the domestic hot water from the appliance.
Important: A small quantity of water will remain in some
components even after the appliance has been drained.
Protect any electrical components when removing items from
the water circuits.
Component Replacement
Refer to Fig 42 and 44 for an indication of the location of the
various components.
Replace any components removed from the appliance in the
reverse order using new gaskets/O-rings/sealant/heat transfer
paste 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 onto lower
lugs, as necessary, to gain access to the components. Refer to
Section 14, Inspection and Servicing.
15.1 Gas Valve
Unscrew the union connections above and below the gas valve
and remove the assembly. Disconnect/unplug the electrical
connections from the valve.
Use new gaskets when replacing the valve. Refer to Fig 48.
Set the Gas Valve:
Connect a pressure gauge to the burner and inlet pressure test
points on the valve. Refer to Fig 39.
Switch on the gas and electricity supplies.
Check for gas tightness at the gas valve inlet.
Refer to Section 12.5 Commissioning for the method of
checking/setting the pressures.
Check for gas soundness at the gas valve outlet.
Adjust the maximum and start pressure [minimum], as
necessary, to obtain the required pressures. Switch off the
appliance and disconnect the pressure gauge. and tighten the
screw. Refer to Section 12.5 and Fig 39 for setting instructions.
Check for gas soundness at the test point.
15. Replacement Of Parts
24
Fig. 48 . Lower casing - gas and water
controls.
1
9
8
7
6
5
4
3
2
1. Gas valve
2. Pump
3. Pressure guage
4. Relief valve
5. Manifold assembly
6. Control panel in lowered position
7. DHW sensor
8. DHW flow turbine
9. Control panel top support
10. Drain tap
11. Drain tube
Fig. 49. Spark electrode assembly
1
3
2
1. Spark electrode assembly
2. Fixing screw
3. Burner blade assembly (LH)
11
10
