Worcester 350 Combi - Page 20

13. Inspection and Servicing
13.1 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 in stal·
lation conditions and usa ge, but once per year sh ould generally
be adequate. The extent of the service required by the appliance is
determined by the operating condition of the appliance when test·
ed by fully qualified engineers.
It is
the law that any service work must be carried out by compe·
tent engineers such as British Gas or Corgi registered personnel.
13.2 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 the ventilation
openings
in the compartment door or wa ll s are clear. See Section 6.
Check the connections in the system and remake any joints or fit·
tings which show signs of leakage. Refi ll , vent and re·pressurise as
described in Section 11 .
Operate the appliance and the hea ting system taking note of any
fault
s.
IMPORTANT . Dis co nnect the electrical supply at the mains and
turn off the gas supply at the gas service cock on the appliance
before servicing. See
Fig. 21 .
After completing the service always test for gas soundness as
indi·
cated in BS 6891 .
13.3 DISMANTLE THE APPLIANCE.
To carry out a full and comprehensive serv ice of the appliance
remove
the following parts to gain access to t he co mpon ents
which need to be checked or serviced:
(a) Cabinet Front Cover. Pull forward at the bottom and lift off the
.
top supports. See Fig . 22.
· (b) Inner Cover PaneL Remove the cabinet front panel. Unscrew
the four screws and remove the panel. See Fig. 22.
· (c) Inner Casing Cover. Remove the cabinet front cover. Unscrew
the four screws and remove the casing cover. See Fig. 22.
(d) Combustion Chamber Cover. Remove the inner casing cover.
Loosen
the two wing nuts securing the flu e hood and remove the
hooks from the combustion chamber cover. Unscrew t he four
screws
and remove the cove r. See Fig. 29.
(e) Fan. Remove t he inner casing cover. Remove by unplugging
the electrical connections
at the terminal block, pu ll ing off the sue·
tion pipes and unscrewing the single fixing screw. Unscrew the flue
duct fi xing clamp. See Fig . 18 .
(a) Appliance with Rear Flue. Carefully slide the fan out of
the appliance ensuring
that the flue duct remains undisturbed.
(b) Appliance with Side Flue. Carefully slide the flue duct out
of
th e fan outlet, to the left or right as appropriate. Unscrew
and remove the flue hood fixing hook at the same si de as the
flue connection.
(f) Flue Hood Assembly. Remove the inner casing cover. Loo sen
the two wing nuts securing the flue hood and remove the hooks
from the combustion chamber cover. Withdraw
the clamping bars
from their rear bracket
and lift the flue hood assembly from the
appliance.
If th e fan is not to be removed separately, then discon·
nect t he electrical supply, the suction tubes and the flue duct as
described in
the pr eceding note. See Fig . 15.
(g) Burner Blade Assembly. R em ove the combustion chamber
cover. Remove
the spark and sensing electrode asse mblies by un·
screwing and removing the mounting brackets complete. See Fig .3 0.
Loosen the two bottom fixing screws and unscrew and remove the
two extended screws securing the burner blade assembly. See
Fig.
31 . Lift the blade assembly off the bottom support screws, raise
the front of the assembly to abo ut 45 ° and carefu ll y withdraw it
from the combustion chamber. Take care not to damage the insu·
Iation pad s.
20
1 3.4 SERVICING OF COMPONENTS.
Clean
the fan. Any dus t of fluff should be re mo ved with a so ft
brush or by blowing. Sharp instruments must no t be used. Take
care not to distort the sensing tubes.
Clean the burner . Brush th e bla de tops with a soft brush and
check tha t all the flame ports are clear. Remove any blockages
with a non-metallic
bru sh. Clean any deposits from t he ven tur is
using a soft
bru sh.
Clean the electrodes . Brush any deposits from the electrodes
using a soft
bru sh. Replace any electrode th at show signs of dam·
age or erosion.
Clean the burner manifold. Inspect t he injectors and carefully
clean with a soft brush.
Do not use a wire brush or anything like ly
to cause damage. Replace any injector which appears damaged .
Don't forget
the spacing washer s.
Clean the Gas to Water heat exchanger. Cover th e burner mani·
fold with a cloth. Clean the heat exchanger using a soft brush .
Remove
the deposits from the bottom of the combustion chamber.
Check the combustion chamber insulation. Examine the insu-
lation pad s and replace if necessary. See Section 14 , Para. 14.4.
Clean the controls. Remove any dus t or deposits wh ic h may have
built up
on the controls. Ta ke care not to mishandle any ca mpo ·
nent connections.
Reassemble the appliance.
Refit the burner blade assembl y, the e lec trodes, the flue hood and
the fa n if it ha s been removed separate ly. Check that the elec·
tra des and suction tubes are connected and positioned correctl y.
See Fig . 30 .
Refi t the combustion chamber cover. Carefully reconnect the flue
duct to
the fan outlet as described in Section 11, Para. 5.
Check that a ll the connections have been made correctly before
refitting
the boiler inner casing cover. See F ig . 22.
Check that the flue terminal is clean and unobstructed .
13.5 TEST THE APPLIANCE.
On completion of the service and reassembly of the appliance,
check f
or gas soundness and the correct operation of the appli·
ance as described in Section 11 .
Refit t he inner cover panel and the cabi ne t front pane l and reset
t
he controls to the user's requirements.