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12.4
APPLIANCE OPERATION
Check that the electrical supply to the appliance is off.
Set the Operating Switch (or Programmer) to
OFF.
Remove the inner casing cover. Refer to Section 14.3(b).
Disconnect the electrical connections from the main solenoid.
Do not leave them unprotected. See Fig. 29. Turn on the gas
supply and reconnect the electricity supply.
Set the Operating Switch (or Programmer) to
HEATING &
WATER.
A continuous ignition spark will occur until the pilot is
alight and sensed by the control circuit. The fan will run but the
main burner will not light. Test for gas soundness at the joint
between the pilot pipe and the burner with leak detection fluid.
Observe the pilot flame. It should be about 18-20 mm long and
envelope the spark electrode tip.
If
not, refer to Section 14.4.
See Fig. 35.
If
the pilot still does not light, contact Worcester
Heat Systems Service Department.
Set the Operating Switch (or Programmer) to
OFF
and discon·
nect the electrical supply at the mains.
Replace the inner casing cover.
Reconnect the electrical connections to the gas valve.Loosen the
burner pressure test point screw and connect a pressure gauge.
See Fig 29.
Domestic Hot Water
Set the Operating Switch (or Programmer) to
WATER
and fully
open a hot tap.
The boiler should light at a burner pressure of between 1 4 and
15mbar (5.6 and 6.0 in. wg.). If the burner pressure is low, check
that the supply pressure at the gas valve is at least 19 mbar (7.6
in.wg).
Note:
The burner pressure is factory set and if (after checking
that the supply pressure is sufficient) the correct pressure is not
obtained then Worcester Heat Systems Service Department
should be contacted.
If
the appliance does not light, check that the it is not in the
overheat 'lockout' state by pressing the thermostat reset button.
See Fig. 30.
Gradually close the hot tap and check that the burner pressure
drops. Fully open the tap and check that the burner pressure ris·
es. Fully close the tap and check that the burner goes off. The
pump will continue running until the appliance has cooled to a
preset temperature.
Set the Operating Switch (or Programmer) to
OFF.
Central Heating
Check that all the radiator valves are open. Set the room thermo·
stat and the Central Heating Temperature Control to maximum.
On sealed systems check that the system is prP.ssurisP.rl anr:l set
to the required pressure as indicated on the gauge.
Set the Operating Switch (or Programmer) to
HEATING
&
WATER.
The burner will light.
The appliance will modulate its output from 9.2 kW (31 ,400
Btu/h) to the set output of 16.1 kW (54, 900 Btu/h) over a peri·
od of about two minutes.
Check the system to ensure that all the radiators are heating up
evenly.
Shut down all but one of the radiators and observe the burner
pressure fall. Open all of the radiator valves and check that the
burner pressure rises.
Balance the system so that the required temperature difference
across the central heating flow and return pipes is obtained. See
Table 3.
Adjust the central heating by-pass valve until the same tempera·
ture difference is obtained. See Fig 31. This should be carried out
with only a single radiator operating. If thermostatic radiator
valves are fitted then one rudiator should be left uncontrolled.
The bypass valve should never be fully closed.
19
If
the heat load is in excess of 16.1 kW (54, 900 Btu/h) then reset
the controls to the maximum of 24 kW (82,000 Btu/h) by care·
fully rotating the adjustment potentiometer to its maximum
postion. Access is gained to the adjustment point by lowering
the electrical control box. Indicate the new setting pressure on
the data plate.
Set the room thermostat to minimum and check that the burner
goes out. Reset the room thermostat to maximum and the burn·
er will relight and follow the normal operating procedure.
Check for proper ignition of the burner after a break in the gas
supply. '!Urn off the gas service cock and wait for 60 seconds.
The main burner and pilot will go out but sparking from the
electrode will continue. Carefully open the gas service cock and
observe the burner relight and follow the normal sequence of
operation.
Set the Operating Switch (or Programmer) to
OFF.
'!Urn off the gas service cock and the electrical supply to the
appliance.
Drain the system while the appliance is still hot.
Refill, vent and, with a sealed system, re·pressurise as described
in Section 12.2.
Domestic Hot Water and Central Heating
'!Urn on the electricity supply to the appliance and open the gas
supply cock at the appliance.
Set the Operating Switch (or Programmer) to
HEATING &
WATER.
If a programmer is fitted, set the domestic hot water to
Continuous or 24Hrs
and the central heating to
ON.
The burner
will light and heat will pass into the system. '!Urn on a hot water
tap and check that fully heated hot water is discharged from the
tap.
Close the tap and the burner will go off. The appliance will then
return to the central heating mode and automatically balance
with the system requirements.
Set the Operating Switch (or Programmer) to
OFF
and the burner
will go out.
12. 5 COMPLETION OF COMMISSIONING
Disconnect the pressure gauge and tighten the test point screw.
Restart the appliance and check for gas soundness around the
test point screw.
Refit the cabinet front panel.
If
the appliance is being passed over to the user immediately,
refer to Section 13 - Instructions to the User and set the controls
to the user's requirements.
If the appliance is to be left inoperative, check that the Operating
Switch is set to
OFF.
'!Urn off the gas service cock and switch off
the electricity supply.
If
there is any possibility of the appliance ctm.l system being left
inoperative during frosty conditions, drain the appliance and
system. For short inoperative periods leave the boiler under the
control of a frost thermostat or operating continuously under
the control of a room thermostat set at 6°C.
.
'
1 3. Instructions To The User
13.1
Tell the user how to operate the appliance and hand over
the Users Instructions leaflet.
13.2
Tell the user what to do if the the heating system is not to
be used in frosty weather.
13.3
Tell the user the sealed system set pressure if applicable.
13.4
Tell the user of the importance of regular servicing. Worces·
tcr
He<:~t
Systems Ltd offer a comprehcm;ivc muintcnunce con·
lrcl(.:l.
13.5
Set the system controls to the user's requirements.
13.6
If an external programmer has been fitted which has a pro··
grammable domestic hot water facility then it is suggested that
Lhis be sel to
Continuous
or the equivalent.
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