Technical data

12.4.2 Pilot operation.
Disconnect the flame sense electrode lead at the control board.
Turn on the gas supply and reconnect the electricity supply.
Put the heating control to MAX (or Programmer to heating and water).
A continuous spark will occur for up to two minutes until the pilot
is alight. The fan and pump 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. See Fig. 34.
Observe the pilot flame. It should be about 20mm long and
envelope the spark electrode tip. See Fig. 34.
Put the temperature control (or Programmer) to OFF and
disconnect the electrical supply at the mains.
IMPORTANT: Replace the inner casing cover and reposition the
pressure vessel. See Fig. 16.
Reconnect the flame sense electrode lead at the control board.
Turn off the gas supply at the appliance.
Loosen the burner pressure test point screw and connect a
pressure gauge. See Fig. 33.
12.4.3 Check the maximum burner pressure.
NOTE: The maximum burner pressure is the same for central
heating and domestic hot water.
Turn the hot water temperature control to MAX and set the
programmer (if fitted) to HW ON.
Turn on the gas supply to the appliance.
Turn on the electricity supply to the appliance.
The burner will light at minimum pressure and increase over a few
seconds to the maximum burner pressure to satisfy the heat bank.
If the required maximum burner pressure is not achieved and
the inlet pressure to the appliance is correct i.e. 20 mbar for
natural gas or 37 mbar for propane which is equivalent to 18.5
or 35.5 mbar at the gas valve inlet, then the burner pressure
must be reset. Refer to Fig.33.
If the heatbank is satisfied then it may be necessary to fully open one
or two hot water taps to ensure the maximum heat requirement.
12.4.4 Check the minimum burner pressure.
NOTE: The minimum burner pressures are different for central
heating and domestic hot water.
The minimum burner pressure to be set is the domestic hot
water pressure.
The central heating minimum burner pressure is a control
function and is not adjustable.
Repeat the procedure for checking the maximum burner
pressure but, carefully, pull-off one of the blue leads from the
modulating control on the gas valve. Ensure that the connector
does not touch any metal. Refer to Fig.33.
If the minimum burner presure is not achieved then the burner
pressure must be reset.
NOTE: The maximum burner pressure must
be set first as this
can affect the minimum burner pressure setting. Refer to Fig. 33.
Turn all the temperature controls to OFF (or MIN) and the
programmer (if fitted) to OFF.
Turn off the gas and electricity supplies to the appliance.
12.4.5 Check the operation of the appliance.
Refer to the Operational Flow Diagrams, Section 16, for the
sequence of events.
The appliance control system gives priority to the satisfying of
the heatbank and the delivery of domestic hot water.
Check that all the system and radiator valves are open.
Set the hot water temperature control MAX. set the programmer
(if fitted) to DHW ON or CONTINUOUS.
Turn on the gas and electricity supplies to the appliance.
The boiler will light and follow the Tank Mode of operation until
the heatbank is satisfied (upto twelve minutes from cold) when
the burner will go off.
Fully open a hot tap to put the appliance into the DHW draw-off
mode. The burner will light to maintain the heatbank which is
supplying the hot water to the tap.
Shut the tap and the burner will go out, possibly after a short
period of time filling the heatbank.
Set the programmer, if fitted, to central heating ON, the hot
water temperature control to MIN, the heating temperature
control to MAX and the room thermostat to MAX. Check that
the system is pressurised , the burner will light and, after a
possible short period topping-up the heatbank, will supply heat
to the radiators.
Check that the radiators heat up evenly.
Balance the system so that the required temperature difference
across the heating flow and return pipes is obtained. See Section
3, Table 4.
Adjust the by-pass valve until the same temperature difference is
obtained. See Fig. 16 and 17. This should be carried out with
only a single radiator operating.
If thermostatic radiator valves are fitted then, ideally, 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.
12.4.6 Check ignition after a break in the gas supply.
Turn 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 re-light and follow the normal sequence of operation.
Put the temperature controls (or Programmer) to OFF. Switch off
the gas service cock and the electrical supply to the appliance.
12.4.7 Drain and reset system.
Drain the heating system whilst the appliance is still hot. Refer to
Fig. 1. for the position of the appliance drain point.
Refill, vent and re-pressurise (sealed systems) as described previously.
Set the temperature controls to MAX. If a programmer is fitted
set to Continuous or 24 Hrs and the Heating to ON. The boiler
will fire and, when the heatbank is satisfied, commence to heat
up the radiators. Allow to operate for 45 minutes, venting as
necessary. Check for water soundness.
Note: From cold it will take about 12 minutes for the heatbank to
be satisfied before the central heating system will receive heat.
IMPORTANT: The complete system must be checked for water
leaks. Should any leaks be found they must be rectified before
proceeding further.
Set the temperature controls to OFF, or if a programmer is fitted,
switch to OFF. Switch electrical supply off at the mains.
Check for the correct operation of User’s Controls including the
room thermostat (if fitted).
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.
Replace the burner pressure adjustment cover. Fix with the screw
and seal with suitable marking e.g red paint.
Refit the expansion vessel and cabinet front panel. See Fig. 16.
If the appliance is being passed over to the User immediately
refer to Section 13, Users Instructions and set the controls to the
user’s requirements.
If the appliance is to be left inoperative check that the
programmer and the controls are set to OFF. Turn the gas service
cock to off and switch off the electricity supply.
For short inoperative periods leave the appliance under the
control of a frost thermostat, if fitted, or operating continuously
under the control of a room thermostat set at 6°C.
If there is any possibility of the appliance and system being left
inoperative during frosty conditions then drain the appliance
and system.
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