Inspection And Servicing - Worcester WR 325 BF Installation And Servicing Instructions

Fig. 7. Gas control slide – shut down position
Gas control slide in this position
If the pressure is not correct then check the gas supply to the
appliance.
If the pressure is correct, turn off the hot water tap and move the
control slide to the off position. See Fig. 7.
Turn off the gas service cock. Remove the pressure gauge and
tighten screw A. See Fig. 4.
(g) Loosen screw D and connect a pressure gauge to the test
point. See Fig. 8.
Re-light the appliance as described in paragraph 9 ( d and e).
(h) Operate the appliance for at least 2 minutes then check that
the burner pressure is as stated in Technical Data – Table 1.
(i) Turn off the hot water tap. Close the gas service cock. Remove
the pressure gauge and tighten screw D.
(j) Re-fit the appliance casing using the four fixing screws. Fit the
plastic Temperature Control Knob housing. Fit the Temperature
Control Knob. Fit the four casing screw covers.
(k) On completion of the commissioning and testing of the
system, the installer should hand over the appliance to the user
with reference to the following:
1. Give the Users Operating Instructions leaflet to the user.
2. Explain and demonstrate the lighting and shutdown
procedures.
3. Advise the user of the precautions necessary to prevent
damage to the system and to the building in the event of
the system remaining inoperative during frost conditions.
4. Stress the importance of an annual service by a competent
heating engineer.
Fig. 8. Gas pressure test point
Piezo igniter
To ensure continued efficient operation of the appliance, it is
recommended that it is checked and serviced as necessary at
regular intervals.
The frequency of servicing will depend upon the particular
installation conditions and usage but in general once a year
should be adequate.
It is the law that any service work must be carried out by a
competent person such as British Gas or other Corgi registered
personnel.
Before commencing any service operation turn off the gas
supply at the main gas service cock.
ACCESS FOR SERVICING
Remove the front casing by removing the four plastic screw
covers and then remove the four fixing screws.
Pull off the Temperature Control Knob.
Unscrew Temperature Control Knob housing.
Lift the casing clear.
10.1 Heat exchanger
Remove the collector hood assembly by slackening the two
retaining screws and pulling the hood out of the flue connector
duct. If the connector duct comes away with the collector hood
separate them and push the connector duct back into the stub in
the balanced flue assembly making sure that it is fully home and
resting against the two stops protruding from the sides of the
stub duct.
Inspect and clean the heat exchanger flueways if necessary.
To remove the heat exchanger, isolate the appliance from the
incoming cold supply and drain down the appliance via the
drain cock fitted.
Disconnect the heat exchanger flow and return pipes at the
water section and the base of the combustion chamber.
Remove the locknuts from the heat exchanger stubs and lift the
heat exchanger clear.
In hard water areas it may be necessary to descale the heat
exchanger body. Either a proprietary brand of descaler or a
solution of 10 parts of water to 1 part of hydrochloric acid
should be used. Fill the heat exchanger with this solution and
leave until the solution stops bubbling. Drain and thoroughly
wash out the exchanger with clean water.
Warning: Acid/water solutions must be used with extreme
caution. Take care not to splash on to the skin or into the eyes.
Wash any affected areas with large amounts of cold water and
seek medical advice.
10.2 Pilot assembly
Inspect the pilot injector and clean if necessary.
Check the pilot burner and electrode are clean and undamaged.
Clean or replace if necessary.
Pull off the pilot filter and clean.
10.3 Main burner
Disconnect the pilot gas pipe and thermocouple at the gas valve
and pull off the red cable from the Piezo unit.
Disconnect the pilot gas pipe from the pilot burner and remove
from the appliance complete with seal. Take care not to lose the
pilot injector.
Remove the two screws retaining the pilot bracket and lift the
complete assembly clear.
Undo the union connection below the burner. Lift the burner
clear and remove.
Inspect and clean the injectors if necessary.
Inspect and clean the main burner bars if necessary.
10.4 Slow ignition valve
Screw out the slow ignition valve (which is located on the right
hand side of the valve above the water flow pipe into the heat
exchanger. Item 17, Fig. 1.
8

10. Inspection and Servicing