Potterton LPG 50e Installation And Servicing Manual page 22

SERVICING INSTRUCTIONS - Page 22
C. Remove screws securing the combustion chamber front
panel and remove panel.
D. Disconnect the fan supply leads from the connec-tor
adjacent to the fan.
E. Remove the screws securing the fan mounting plate
leaving in place the three screws identified with a red circle
or adjacent 'F' mark in fan plate.
Remove mounting plate complete with fan.
F. Disconnect the two flexible tubes from the flue elbow or
adapter.
G. Loosen the two brass securing nuts beneath the flue elbow
outlet and remove the other two. Tilt the flange and
withdraw the elbow. Take care not to damage the gasket.
On vertically flued boilers remove the four brass nuts and
slide the vertical flue adapter up into the flue duct.
H. Unscrew the four nuts and lift off the fluehood taking care
not to damage the rope seal. Lower and lift out vertical flue
adapter.
I. Undo the union on the gas service cock outlet.
J. Unplug the electrical supply leads for the gas control valve
from the control box. See FIG. 29.
K. Remove the screw securing the gas control valve to its
support bracket. See FIG. 29.
L. Disconnect electrode lead from electrode.
M. Remove two screws securing the burner assembly to the
bottom of the boiler case and lift out the burner and gas
control assembly.
2. HEAT EXCHANGER
A. Working from above and below the heat exchanger use a
suitable brush and remove all deposits from between the
fins.
Slide vertical flue adapter into flue duct.
B. Refit the fluehood, ensuring that the rope seal is
undamaged and that a GOOD SEAL is made with the heat
exchanger. Fully tighten the four nuts.
C. Slide the flue elbow into the flue duct or lower flue adapter
and secure to the fluehood using four nuts. Ensure that the
gasket between the fluehood and elbow or adapter is
undamaged and a good seal is obtained.
D. Reconnect flexible tubes to elbow or adapter. NOTE: Red
tube connects the front aluminium tube in the upper
chamber to the lower connection on elbow or adapter each
being identified with a red ring.
3. PILOT BURNER
The following operations are only necessary if the pilot flame is
distorted or the wrong size, i.e. too small.
A. Unscrew the pilot tube from the pilot assembly. Take care
not to damage the electrode.
B. Unscrew the two hexagonal head screws securing the pilot
to the main burner and remove the pilot assembly.
C. Lightly brush the pilot to remove any deposits.
Unscrew the pilot injector and clean its orifice or replace.
NOTE: Do not use a wire brush or pin to clean injector.
D. Gently clean any deposits from the electrode.
E. Refit the pilot injector to the pilot burner and assemble the
pilot to the aluminium tube.
F. Secure the pilot assembly to the main burner using two
hexagonal screws.
G. Fully tighten the union nut connecting the tube tothe pilot.
Check for gas soundness at this joint by following the
procedure described in the commissioning section of these
instructions, Page 18.
spark gap is as illustrated in FIG. 30.
H. Ensure that the
FIG. 30 PILOT BURNER SPARK GAP TOLERANCES
PILOT FILTER
The pilot burner is protected from blockage by a pilot filter
situated within the gas control valve. The filter is large and
designed to last the life of the gas control valve under normal
operating conditions, it is therefore unlikely to need replacing.
However in the event of pilot filter blockage being suspected
the complete control valve should be replaced.
4. COMBUSTION CHAMBER INSULATION
A. Check the combustion chamber insulation for damage. If
damaged replace as described under replacement.
5. MAIN BURNER
A. Lightly brush any deposits from the top of each blade and
ensure there is no fluff in the entry of the burner venturi. If
on re-assembly the burner flame picture is incorrect or the
correct gas rate or burner pressure cannot be obtained,
remove the burner and gas control assembly and
thoroughly clean the burner. Clean or replace the injector.
In the event of the above procedures not rectifying the
flame appearance, disconnect the burner from the gas
control valve at the flanged connection and replace the
burner and injector.
B. Refit the burner and gas control valve assembly into the
boiler, ensuring that the locating pin on the rear of burner
engages correctly into the rear support bracket. Make sure
that the sealing gasket is in place and undamaged
between the burner flange and the case. Secure the
assembly with two screws.