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Remove the clip-on facia bottom cover and controls connections
cover. Refer to Fig 29.
Slide down the access panel to display the mode switch and the
adjusting tool. Refer to Fig 37.
12.6 Checking the Burner Pressure
Check that all the radiator valves are open.
Check that the system is pressurised and set to the required
pressure as indicated on the gauge.
Set the temperature control knobs to maximum and the
clock/programmer to operate continuously.
Turn on the gas and electricity supplies.
Set the mode switch to MAX using the mode adjuster tool. Refer
to Fig 37 and 38. NOTE: Two red lights will flash rapidly on the
facia.
Fig.37. Mode control cover
Mode adjuster
Facia
Fig.38. Mode adjustment
A continuous spark will occur until the burner is alight and
sensed by the control circuit. The burner will remain at its
maximum domestic hot water pressure for one minute. Refer to
Table 1.
It should not be necessary for the gas valve to be adjusted.
Note: The burner pressure is factory set and if, after checking
that the dynamic (working) supply pressure is sufficient i.e.
18.0mb (NG) approx, or 36mb (LPG) at the gas valve inlet
pressure test point, the correct pressure cannot be obtained then
Worcester Heat Systems Service Department should be
contacted.
If the appliance does not light then check that it is not in the
'lock-out' state by pressing the reset button. Refer to Fig 39.
Set the mode switch to Normal.
The burner pressure will drop to the minimum setting and will
ramp up to the maximum central heating pressure appropriate
to the appliance and the gas. Refer to Table 1. It should not be
Mode adjustment cover
Central heating limit
potentiometer
Max/Min switch
Not operational
19
necessary for the central heating potentiometer to be adjusted to
change the burner pressure. If adjustment is required then the
adjusting tool is used to alter the setting of the potentiometer.
Refer to Fig 38.
Set the mode switch to MIN. NOTE: Two red lights will flash
rapidly on the facia.
The burner pressure will drop to the minimum pressure
appropriate to the appliance and the gas for both the central
heating and domestic hot water modes. Refer to Table 1. It
should not be necessary for the central heating potentiometer to
be adjusted.
Test for gas soundness at the joint between the burner and the
gas valve with leak detection fluid.
Set the mode switch back to Normal.
Turn the electricity supply off and then back on to reset the controls.
Replace the facia cover panels.
12.7 Domestic Hot Water
Turn the central heating temperature control knob fully anti-
clockwise. Refer to Fig. 39.
Open a hot tap near the appliance. The burner will light and go
to the maximum burner pressure appropriate to the appliance
and the gas . Refer to Table 1.
Gradually close the tap and check that the burner pressure falls.
Fully open the tap and check that the pressure rises.
Close the tap and check that the burner goes out.
The fan may continue running until the appliance has cooled to a
pre-set temperature.
12.8 Central Heating
Check that all the radiator valves are open.
Check that the system is pressurised and set to the required
pressure as indicated on the gauge.
Check that the clock/programmer is set to operate continuously.
Set the room thermostat and the central heating temperature
control to maximum.
The burner will light and the appliance will modulate its output
from minimum to maximum over a period of about two minutes.
Check that all the radiators are heating up evenly.
Shut down all but one of the radiators and observe the burner
pressure fall. Open all the radiators and check that the burner
pressure rises.
12.9 Balance the system to give a temperature differential of
11°C. A non-adjustable by-pass is fitted to the appliance.
12.10 Set the room thermostat to minimum and check that the
burner goes out. Reset the room thermostat to maximum and
the burner will re-light and follow the normal operating
procedure.
Turn off the gas service cock. The burner will go out but sparking
from the electrode will continue for 10 seconds when the
appliance will 'lock-out'. After 60 seconds carefully open the gas
service cock, press the reset button and observe the burner re-
light and follow the normal sequence of operation. Refer to Fig 6 and 39.
Turn off the gas service cock and the electricity supply to the
appliance.
Drain the system while the appliance is hot.
Refill, vent and re-pressurise the system as described in Section
12.1 preceding, adding, if necessary, a suitable proprietary
inhibitor. Further information is available from Betz Dearborn
0151 420 9563 or Fernox 01799 550811.
12.11 Domestic Hot Water and Central Heating
Set all controls to maximum.
Turn on the electricity supply to the appliance and open the gas
service cock at the appliance.
The burner will light and heat will pass into the system. Turn on
a hot tap and check that hot water is soon discharged from the
tap. Close the tap.
The appliance will then return to the central heating mode and
automatically balance with the system requirements.
Turn off the appliance.
12.12 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.
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