Worcester 24CDi Installation And Servicing Instructions Download Page 20

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15.1 SERVICING
To  ensure  continued  efficient  operation  of  the  appliance  it
must  be  checked  and  serviced  as  necessary  at  regular
intervals.  The  frequency  of  servicing  will  depend  upon  the
particular  installation  conditions  and  usage,  but  once  per
year should generally be adequate. The extent of the service
required  by  the  appliance  is  determined  by  the  operating
condition  of  the  appliance  when  tested  by  fully  qualified
engineers.
Any  service  work  must  be  carried  out  by  competent
engineers such as British Gas or Corgi registered personnel.
15. 2 PRE-SERVICE INSPECTION

Check that the flue terminal and the terminal guard, (if fitted), are clear.
If the appliance is in a compartment, check that any ventilation
openings in the compartment door or walls are clear. See Section
6 - Air Supply.
Check the system and remake any joints or fittings, if necessary,
which show signs of leakage. Refill, vent and re-pressurise as
described in Section 13.2.
Operate the appliance and the system taking note of any faults.

Measurement of the Flue Gases

For consistency of results of the flue gas measurements it is
necessary to have a constant output and stationary equilibrium.

Switch on the appliance.
Switch to DHW and CH mode.
Hinge down the facia.
Turn the Mode Switch to the “Max.” position.
Wait until the appliance reaches stationary equilibrium
(approx. 10 minutes).
Remove the cap from the sensing point. See Fig. 18.
Insert the probe into the measurement gap up to a depth of
50mm.
Seal any gaps.

Expected measurements should be between:

CO: 0.001 and 0.003%.
CO

: 6.7 and 7.0%.

After taking the measurement:

Replace the sealing cap.
Turn the Mode Switch back to the “normal” position.
Put the facia back in to its normal position.

SAFETY
Disconnect the electrical supply at the mains and turn off the
gas supply at the gas service cock on the appliance before
servicing.
After completing the service always test for gas soundness as
indicated in BS 6891.
15. 3 COMPONENT ACCESS

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.

Remove by lifting off the supports.

(b) Inner Casing Cover.

Check that the electricity supply to the

appliance is turned off. Remove the cabinet front panel. Unscrew the
four screws securing the cover to the casing and lift off. See Fig. 26.

Check that the electricity supply to the appliance

is  turned  off.  Remove  the  cabinet  front  panel.  Unscrew  the  two
upper  screws  as  shown  in  Fig.12  and  hinge  down  the  facia
taking  care  not  to  distort  the  pressure  gauge  capillary  tube  or
electrical connections.

(d) Bottom panel.

Hinge down the facia panel. Disengage the

front edge of the bottom panel from the two clips and remove
the bottom panel from the appliance.

(e) Fan.

Remove the inner casing cover. Carefully unplug the

electrical connections and pull off the sensing tubes. Unscrew
the three fixing screws and remove the fan assembly. See Fig. 31.

(f) Flue Hood Assembly.

Remove the fan assembly. Undo the

two screws securing the flue hood. Lift and slide the flue hood
assembly from the appliance. See Fig. 31. When refitting the
hood ensure that the rear return edge passes under the lip at the
rear of the combustion chamber.

(g) Combustion Chamber Front and Sides.

Remove the inner

casing  cover.  Slacken  off  to  the  end  of  the  thread  but  do  not
remove  the  two  wing  nuts  securing  the  combustion  chamber.
Unhook  the  securing  rods  out  of  the  locating  holes  in  the
combustion chamber sides. Ease the combustion chamber front
and side assembly clear of the appliance. Refer to Fig. 31.

(h) Burner Assembly.

Remove the combustion chamber front

and sides. Pull off the two spark electrode leads and disconnect
the flame sense lead at the plastic connector under the inner
casing.

NOTE:

The flame sensing lead is attached to the burner.

When the burner is removed ensure this lead is fed through the
inner casing. Remove the grommet seal to allow the plastic
connection to pass through the inner casing. Unscrew the G

union nut on top of the gas valve and retain the sealing washer.
Unscrew the front burner fixing screw. Lift the burner and ease
the union nut through the inner casing sealing grommet.
Remove the burner assembly clear of the inner casing.
Ensure the flame sensing lead passes through the base of the
inner casing. See Fig. 31 and 32.

15. 4 SERVICE OF COMPONENTS
Clean the Fan.

Any dust or fluff should be removed with a soft

brush or by blowing. Take care not to distort the pressure
sensing device.

Clean the Main 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.  Inspect  the
injector  and  clean  with  a  soft  brush.  Replace  the  injector  if  it
appears damaged. Do not use a wire brush or anything likely to
cause  damage.  Replace  the  spark  and  sense  electrodes  if  they
appear damaged.

15. Inspection And Servicing

Fig. 31. Appliance components and fixings

(upper assembly).

Fan assembly
fixing screws (3)

Sensing tubes
(Red to +)

Flue hood
fixing
screws

Overheat
thermostat

Fan
assembly

Flue hood

Combustion
chamber
fixing bolts
(2)

Burner fixing screw
(35CDi

2 screws)