Instructions To The User - Worcester WM 12 Installation And Servicing Instructions

10. Check all of the air-ways to the burner are clear of any
obstruction.
12.5 Check the Burner
1. Hang the burner on the burner hanging bracket situated on
the bottom left hand side of the external duct (see fig. 30).
2. Check the nozzle and electrode settings are correct for the
burner (see fig. 28).
3. Check the nozzle lies central with the combustion head hole.
4. Check for any visible defects.
12.6 Replace the burner
1. Check the burner flexible oil lines are connected correctly to
the connection block, as shown in figs 9 to 11and in Section
11.5 Oil supply installation.
2. With the sponge O-shaped gasket around the burner blast
tube insert the burner into the burner mounting flange ensuring
the cut out in the gasket lines up with the burner retaining screw.
Push the burner firmly forward to compress the gasket and
tighten the burner retaining screw located to the left of the burn-
er control box using a 4mm hexagon driver.
Note: It is important that a good seal is made between the burn-
er and the boiler to prevent re-circulation of flue gases from the
combustion chamber to the burner inlet.
3. Re-connect the burner electrical plug lead into the external con-
trol box.
12.7 Fit a pressure gauge and manifold to the burner pump at
the point indicated in Fig. 10.
12.8 Switch the service switch to the 'OFF' position (see fig. 29).
12.9 Turn on the electricity to the appliance.
12.10 Bleed the burner
Two Pipe System
A two pipe system will automatically vent the air back to the oil
tank but it is recommended to use the single pipe system
method of bleeding the burner as descibed below to quicken the
removal of air from the inlet oil line. Set the programmer to
heating and hot water and turn on the boiler thermostat.
Switch the service switch to 'RUN' position as shown in fig. 29
and allow the burner to run through to lockout. Reset the burner
control box and repeat the procedure until the burner fires and
runs in a steady state. This may take several attempts depending
on the oil pipe length and height.
Single pipe systems only
Release the fuel bleed port on the manifold and place a suitable
receptacle beneath. Set the programmer to heating and hot
water and turn on the boiler thermostat. Switch the service switch
to 'RUN' position as shown in fig. 29 and allow the burner to run
through to lockout. Reset the burner control box and repeat the
procedure at least three times or until a steady stream of oil, with-
out air, is exhausted from the bleed port. Re-lock the bleed port.
12.11 Adjust the air shutter and pump pressure to the settings recom-
mended in Table 2. After a pre-ignition period of approximately 15 sec-
onds the burner should ignite. Flame sensing is carried out by means of
a photocell mounted in the burner body. Should the boiler fail to estab-
lish a normal firing pattern (or should flame failure occur during run-
ning), the absence of a flame is sensed and the control box is monitored
to a safe lockout condition and the boiler is shut down. The lockout
indicator light in the boiler control panel will illuminate and the reset
button on the burner control box will continue flashing indicating that
the burner has gone to lockout. In this instance press the lockout reset
button mounted in the burner control box. Another start sequence is
then initiated. Repeat the procedure until a flame is established.
Note: Persistent lockout when running indicates a fault and a
Service Engineer should be consulted.
12.12 Run the boiler for approximately 3 minutes and switch
off using the service switch checking that there is no after-spurt-
ing from the nozzle. This can be detected by oil saturation on
the blast tube. If after-spurting occurs remove the burner from
the boiler, unscrew the nozzle, and while holding the burner in a
vertical position, fill the nozzle holder with oil. Refit the burner
and continue to run the boiler for three minute periods until
after-spurting stops.
12.13 Run the boiler for a further 15 minute period and then final-
ly fine tune the air shutter setting to give the CO
Table 2 less 0.5% CO . During this period some smoke will be emit-
2
ted due to the burning of the organic binder in the insulation box.
Smoke readings will therefore be inaccurate at this point.
Note: Flue gas sampling is taken with the probe or smoke pump
positioned in the flue centrally by approximately 150mm.
12.14 Check that the smoke reading is in the range 0-1. If this
cannot be achieved then check that the burner head is set cor-
rectly and the nozzle is in good condition.
12.15 Check that the flue temperature does not exceed the
value specified in Table 2. If this is the case then check that the
baffle is correctly located. If the baffle is correctly located then
reduce the pump pressure since nozzle variations of up
to+or–15% may occur.
12.16 Remove the oil pressure gauge and manifold and check
all oil system joints for any signs of leakage.
NOTE: Check that the oil hoses do not touch hot surfaces.
12.17 Refit the external cover in reverse order to that described
in Section 5.
12.18 Allow the burner to run for a further five minutes and
then recheck the CO level and adjust the air setting if required.
2
12.19 When the heating circuit has reached full operating tem-
perature check the whole system for any leaks.
12.20 Refit the cabinet inside the property in reverse order to
that described in Section 5.
12.21 Locking the Boiler
Provision has been made to lock the external cover to the burn-
er hanging bracket using a padlock. A suitable padlock is the
P73 manufactured by Yale Security Products, or use a padlock
which has 20 to 22mm between the two centres on the shackle
and 15 to 20mm between the body and inside of the shackle. A
slot and hole have been provided underneath the external cover
to fasten the cover using a padlock.
NOTE: After commissioning the appliance the engineer should
position the service switch in the RUN position as shown in fig. 29.

13. Instructions to the User

13.1 Hand the users instructions to the user or purchaser for
retention and instruct them in the efficient and safe operation of
the appliance and the heating/hot water system.
13.2 Advise the user or purchaser of the precautions necessary
to prevent damage to the heating/hot water system and to the
building in the event of the heating system remaining inopera-
tive during frost conditions.
13.3 Finally advise the user or purchaser that for continued efficient
and safe operation of the appliance it is important that adequate
servicing is carried out by a qualified engineer at least once per year.
13.4 Worcester, Bosch Group will be pleased to discuss and
offer a comprehensive maintenance contract.
Set the system controls to the users requirements.
27
level specified in
2