Replacement Of Parts - Worcester Highflow 400 RSF Installation And Servicing Instructions

Controls.
Remove any dust or deposits using a soft brush. Take care not to
mishandle any component connections.
NOTE: Should any of the components be damaged they must be
replaced before the service is completed. Refer to the appropriate
item in Section 15 "Replacement of Parts."
After servicing, reassemble the appliance in the reverse order.
Check that all components are in place and correctly fixed. See
Fig.16 and 35. Leave the cabinet front panel to be fitted after
checking the operation of the appliance.
14.4 Test the Appliance.
On completion of the service and reassembly of the appliance,
check for gas soundness and the correct operation of the
appliance as described in Section 12 - Commissioning.
Refit the cabinet front panel and reset the controls to the users
requirements.

15. Replacement of Parts

WARNING. Switch off the electricity and gas supplies before
replacing any components. After the replacement of any
components check for gas soundness (where relevant) and carry
out functional checks as described in Section 14.
15.1 COMPONENT ACCESS.
To replace components:
It is necessary to remove one or more sections of the cabinet and
cover plates within the appliance. Refer to Section 14.2 a, b, c
and d.
To access the control box:
Place the facia and control box in the Service Position. Refer to
Section 14.2, (b) and Fig. 14. Pull the two thermostat knobs clear
of the facia. Unscrew two fixing screws at the top and two on the
underside securing the facia to the control box. Ease the facia
clear of the control box. Take care not to over stretch the
capillary tubes or wiring. Ensure the facia is supported when out
of the control box. See Fig. 14.
IMPORTANT:
The following components are secured to the appliance with
clips, screws, union fittings or "O " ring seals to ensure the joints
are water sound. See Fig. 16.
Expansion Vessel.
Circulating Pump.
Water Diverter Valve.
Water to Water Heat Exchanger.
Gas to Water Heat exchanger.
Flow switch.
Gas valve.
Pressure relief valve.
Comprehensive gasket/ O-ring packs are available for the gas
and water connections on the appliance.
Refer to Section 18 - Short Parts List.
When replacing these components the connections must be fully
entered so that the clips can pass completely into the locating
groove. The clips must not be forced into place.
When a component is replaced or disturbed it is recommended
the "O" is replaced.
The "O" rings can be lubricated with a suitable lubricant (i.e.
silicon based grease or glycerine) which is non-reactive with the
ethylene - propylene nitrile "O" rings.
15.2 Draining The Appliance.
Check that the electricity supply to the appliance is turned off.
Remove the kick strip secured to the cabinet side panels and
base plate with five screws. See Fig. 14.
Before removing any component holding water it is important
that as much water as possible is drained from the appliance.
CAUTION: Some water will remain in the expansion vessel,
pump, water diverter valve, water to water heat exchanger and
gas to water heat exchanger. Extra care must be taken when
removing these components.
Place a towel or cloth beneath the component to absorb the
excess system water.
The water will be contaminated and any absorbent material
used must be destroyed or washed thoroughly after any
component has been replaced.
(a) Appliance Heatbank and Heating Circuit:
Turn off the central heating flow and return valves at the
appliance using a flat blade screwdriver. See Fig. 17. Fit a tube to
the drain tap located on the right hand side, front, of the
heatbank and open the tap. See Figs. 16.
NOTE: The heatbank contains about 60 litres (13.5 gallons) of
primary water sufficient time must be allowed to drain the
heatbank. Close the drain tap when the flow has stopped.
(b) Appliance Hot Water Circuit:
Turn off the mains water supply valve at the appliance using a
flat blade screwdriver. See Figs. 16 and17. Fit a tube to the drain
tap located on the left hand side of the gas valve. See Fig. 16.
Open the tap and drain the hot water circuit.
A quantity of water will remain in the water to water heat
exchanger, extra care must be taken when removing this
component.
15.3 COMPONENT REPLACEMENT.
1. Automatic Air Vent. See Figs. 16, 17 and 35.
Check that the electricity supply to the appliance is turned off.
Remove the cabinet front panel, place the facia and control box
in the Service Position, lower the expansion vessel into the
Service Position and remove the inner casing cover, as described
in Section 14.2 a, b, c and d.
Drain the heating circuit as described in Section 15.2 (a).
Unscrew the automatic air vent and discard. Fit the replacement
assembly. Ensure the plastic cap is removed and discarded.
Open the valves, fill and re-pressurise the system as described in
Section 12.2.
Ensure the joint is water tight. Reassemble the appliance in the
reverse order.
2. Fan. See Figs. 9, 16 and 35.
Check that the electricity supply to the appliance is turned off.
Remove the cabinet front panel, place the facia and control box
in the Service Position, lower the expansion vessel into the
Service Position and remove the inner casing cover, as described
in Section 14.2 a,b,c and d.
Remove the fan assembly as described in Section 14.2 (e) and
discard.
Fit the replacement fan in the reverse order.
Reassemble the appliance in the reverse order.
3. Gas to Water Heat Exchanger. See Figs. 9, 16, 17, 35 and 36.
Check that the electricity supply to the appliance is turned off.
Remove the cabinet front panel, place the facia and control box
in the Service Position, lower the expansion vessel into the
Service Position and remove the inner casing cover, as described
in Section 14.2 a, b, c and d.
Drain the heating circuit as described in Section 15.2 (a).
Remove the fan, flue hood, combustion chamber cover as
described in Sections 14.2 e, f and g. Remove the Safety
Temperature Limiter Thermostat phial from the thermostat
pocket as described in Section 15.3 - 11.
Remove the left hand fibre insulation pad from the combustion
chamber. Remove the access cover in the left hand side of the
combustion chamber held in position with one screw. Unscrew
the front and rear heat exchanger union connections.
Lift the heat exchanger off the right hand side of the combustion
chamber support and clear of the union connections. Remove
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