Worcester Highflow 400 BF, Installation And Servicing Instructions

21

openings in the compartment door or walls are clear. Refer to
Section 6, Air Supply.
Check the operation of the pressure relief valve. Reset the system
pressure if necessary. 
Check the expansion vessel pressure and reset as necessary.

Check the system and remake any joints or fittings which show
signs of leakage. Refill, vent and re-pressurise sealed systems as
described in Section 12, Commissioning.

Operate the appliance and the system taking note of any faults.

Measurement of flue gases

For consistancy of flue gas measurements it is necessary to have a
constant maximum output and the appliance to be at equilibrium.

Insert the probe into the secondary flue.

Expected readings should be approximately:

CO

0.003—0.008%

CO

2

7.0—8.0% 

SAFETY: Disconnect the electrical supply at the mains and
turn off the gas supply at the gas service cock on the
appliance before servicing the appliance. See Fig. 12.

After completing the service always test for gas soundness as
indicated in BS 6891.

14.2 DISMANTLE THE APPLIANCE

To carry out a full and comprehensive service of the appliance
remove the following parts to gain access to the components
which need to be checked or serviced.

(a) Cabinet Front Panel

Lift the panel to clear the top locator and kick strip.

(b) Facia and Control Box

Remove the cabinet front panel. Unscrew the two screws
securing the facia to the outer edges of the cabinet, accessible
under the facia. Ease the facia forwards on the slide rails until
fully extended. Lift the facia and control box upwards through
90° into the Service Position. Lodge in the Service Position on the
outer locations. See Fig. 12.

(c) Expansion Vessel

Remove the cabinet front panel

Unscrew the screw securing the expansion vessel support
bracket to the right hand side panel. Lower the vessel gently
until resting on the floor. See Figs. 16 and 37.

(d) Inner Casing Cover

Repeat operations a,b and c. Unscrew the four screws securing
the cover to the inner casing and lift off. See Figs. 16 and 23.

(e) Flue Hood

Repeat operations a, b, c and d. Unscrew the two screws locating
the front of the flue hood to the combustion chamber cover. Ease
the flue hood forwards about 15mm to clear the rear locator.
Remove the flue hood from the heat exchanger and clear of the
inner casing. See Figs. 16 and 23.

(f) Combustion Chamber Cover

Repeat operations a, b, c, d, and e. Unscrew the four screws
securing the combustion chamber cover and remove the cover.
See Figs. 16 and 23.

(g) Burner

Repeat operations a, b, c, d, e and f. Unscrew the two screws
securing the pilot bracket to the burner. Unscrew the two screws
securing the front of the burner and the spark electrode lead to
the burner bracket located inside the inner casing. Remove the
burner by easing forwards and upwards off the main burner
injector and clear of the pilot bracket. See Figs. 16 and 23.

(h) Pilot

Repeat operations a,b,c,d,e,f and g. Unscrew the two screws securing
the pilot bracket to the burner bracket. Unscrew and remove the
flame sense electrode. Unclip the spark igniter and remove.
Support the pilot bracket with a suitable tool. Unscrew the pilot
pipe union nut and ease the pipe clear of the bracket. Remove
the pilot injector from the pilot bracket. See Figs. 16 and 23.

14.3 SERVICING OF COMPONENTS
Clean the Burner

Brush the blade tops and mixing tube with a soft brush and
check that all the flame ports are clear. Remove any blockages
with a non-metallic brush.

Clean the Main Burner Injector

Inspect the main burner injector located at the rear of the inner
casing. Clean with a soft brush. Do not use a wire brush or
anything likely to cause damage.

Clean the Pilot Bracket

Brush with a soft brush. Clean the pilot injector by rinsing it in
warm water. Check the condition of the electrode.

Clean the Gas to Water Heat Exchanger

Cover the main burner injector and pilot bracket with a cloth. Clean
the heat exchanger using a soft brush. Remove the deposits from
the bottom of the combustion chamber. The heat exchanger is
manufactured from copper take care not distort any of the fins.

Combustion Chamber Insulation

Examine and replace any pads that are damaged. Refer to
Section 15.3.3.

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 23. 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.

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 12.

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. 12. 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
strain the wiring. Ensure the facia is supported when out of the
control box. See Fig. 12.

IMPORTANT:

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 components that use clip fixings, 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.
Any “O” ring which shows sign of damage must be replaced. The
“O” rings can be lubricated with a suitable lubricant (i.e. silicon
based grease or glycerin) 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.
Before removing any component holding water it is important
that as much water as possible is drained from the appliance.

15. Replacement of Parts