Set the movable pointer on the pressure gauge to coincide with
the indicating pointer giving a permanent record of the set
system pressure.
If the pressure indicated on the pressure gauge is greater than
2.6 bar when operating at the maximum central heating
temperature, an extra expansion vessel must be fitted to the
system as close as possible to the appliance central heating
return connection.
The appliance (as dispatched) can accommodate a system volume
of about 83 litres. Refer to BS 7074 Part 1. If the system volume is
in excess of that accommodated by the expansion vessel fitted to
the appliance then an extra vessel must be fitted as close as
possible to the central heating return connection of the appliance.
Any extra vessel fitted must be pressurised to the same figure as
the integral vessel. If the expansion vessel fails then the specified
replacement must be fitted.
12.3 PROGRAMMER
Any programmer fitted on the appliance should be set up at this
stage following the instructions sent with the programmer.
The programmer will retain the setting for up to three weeks
following an interruption in the electricity supply.
12.4 APPLIANCE OPERATION
Turn off the gas and electricity supplies to the appliance.
Loosen the burner pressure test point screw and connect a
pressure gauge. See Fig. 25.
Undo the two screws and hinge down the facia.
Setting the Burner Pressure
Check that all the radiator valves are open. Set the room
thermostat and the Central Heating Temperature Control to
maximum.
On sealed systems check that the system is pressurised and set
to the required pressure as indicated on the gauge.
Set the Operating switch (or Programmer) to HEATING & WATER.
Set the gas valve mode switch, at the rear of the facia, to the Test
Max. Position.
Turn on a hot water tap.
Turn on the gas and electricity supplies.
A continuous ignition spark will occur until the burner is alight
and sensed by the control circuit. The burner will light and remain
at its maximum domestic hot water setting. The burner pressure
should be 12.1 mbar for natural gas and 35.5 mbar for propane.
Set the gas valve mode switch to the Test Min. position.
The burner pressure will drop to the minimum setting for both
central heating mode and domestic hot water mode. The burner
pressure should be 1.0 mbar for natural gas and 3.8 mbar for
propane.
Set the gas valve mode switch to the normal operation position.
Turn both the central heating control knob and the domestic water
control knob to their maximum position (i.e. fully clockwise).
Turn off the hot water tap.
The burner pressure will drop to minimum setting and will
ramp up to the maximum central heating setting. The burner
pressure should be 8.8 mbar for natural gas and 24.3 mbar for
propane.
Test for gas soundness at the joint between the burner and the
gas valve with leak detection fluid.
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 it is not in the
“lockout” state by pressing the lockout reset button. See Fig. 27.
Set the gas valve mode switch back to the normal position.
Turn off the electricity supply and then back on again to reset the
controls.
Domestic Hot Water
First of all a tap should be opened. Gradually close the hot tap
and check that the burner pressure drops. Fully open the tap and
check that the burner pressure rises. Fully close the tap and
check that the burner goes off. The fan may continue running
until the appliance has cooled to a pre-set temperature.
Set the operating switch to OFF.
Central Heating
Set the mode switch to the normal position.
Check that all the radiator valves are open. Set the room
thermostat and the Central Heating Temperature Control to
maximum.
On sealed systems check that the system is pressurised and set
to the required pressure as indicated on the gauge.
Set the Operating Switch (and Programmer) to HEATING & WATER.
Turn on the gas and electricity supplies.
The burner will light.
The appliance will modulate its output between 9.0 and 24.0 kW
over a period 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, page 4.
Adjust the central heating by-pass valve until the same
temperature difference is obtained. See Fig. 26. This should be
carried out with only a single radiator operating. If thermostatic
radiator valves are fitted then one radiator should be left
uncontrolled. The bypass valve should never be fully closed.
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.
Check for proper ignition of the burner after a break in the gas
supply. Turn off the gas service cock and wait for 60 seconds. The
burner will go out but sparking from the electrode will continue
for 10 seconds when the appliance will enter a ‘lockout’ state.
Carefully open the gas service cock, press the lockout reset
button and observe the burner re-light and follow the normal
sequence of operation.
Set the Operating Switch to OFF.
Turn 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
Set the gas valve mode switch to the normal position.
Turn on the electricity supply to the appliance and open the gas
supply cock at the appliance.
Set the Operating Switch (and 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. Turn 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 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 users requirements.
If the appliance is to be left inoperative, check that the Operating
Switch is set to OFF. Turn off the gas service cock and switch off
the electricity supply.
If there is any possibility of the appliance and system being left
inoperative during frosty conditions, drain the appliance and
system. If the premises are to be left unoccupied during frosty
conditions, then drain the appliance and system. For short
inoperative periods, leave the appliance under the control of the
built in frost thermostat or the remote frost thermostat (if fitted) or
leave operating continuously with the room thermostat set at 6°C.
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