Technical data

17
5.3 TEST FOR GAS SOUNDNESS AND PURGE THE SUPPLY
1. With the boiler gas service cock closed (spindle flats at right angles to valve). Pressure test the gas supply and inlet
pipework connection to the boiler gas service cock for soundness in accordance with BS 6891.
2. Loosen the gas inlet pressure test point screw on the gas valve (see Fig. 17). Ensure the gas supply is on and open the
boiler service cock to purge in accordance with BS 6891.
3. Retighten the test point screw and test for gas soundness. Close the boiler gas service cock.
5.4 INITIAL LIGHTING - Refer to Fig. 16
Note: Remove the protective plastic coating from the boiler painted panels before lighting.
1. Ensure that the gas and electrical supplies to the boiler are off and that the mains water inlet valve and the central heating
flow and return valves are open.
2. Turn on the gas and electrical supplies to the boiler.
3. Ensure all external controls are calling for heat. If the optional Clock is fitted, refer to the User's instructions, set the time
and ensure the Clock is in an 'on' mode.
4. Set the hot water and central heating temperature selectors to maximum.
5. Set the selector switch to
(DHW only).
240XP only - Light the pilot
Depress the gas valve control, allowing gas to the pilot. The micro switch on the gas valve is switched on when the control is
depressed. The fan will operate at full speed. When the air pressure switch is proved, after a delay of about 10 seconds, a spark
will light the pilot.
Warning: If the pilot does not stay alight, release the gas control and turn it clockwise (about ¼ turn). Wait 3 minutes and
repeat lighting procedure.
When the pilot remains alight, continue to hold the gas control in for a further 20 seconds, then release it: the pilot should
remain alight and can be viewed through the window in the room sealed chamber panel.
When the gas control is released, the fan goes to slow speed.
6. Open a hot water tap, the main burner will light and the boiler will provide hot water. Close the tap and the burner will go out.
7. Set the selector switch to
(CH and DHW). The boiler will now run in the central heating mode. The pump will start,
the fan will start; once the pressure switch is proved, the main gas valve solenoid will open allowing the main burner to
light from the ignition electrodes, or pilot in the case of the Alpha 240XP boiler.
5.5 CHECK THE BURNER PRESSURES - Fig. 17
Turn the boiler off. Loosen the burner pressure test point screw on
the gas valve and connect a pressure gauge. Allow the boiler to
run for 10 minutes and check the burner pressures.
Hot water mode
1. Set the selector switch to
(DHW only) and fully open a hot
water tap.
2. The burner will light at the ignition rate and the burner
pressure will increase to maximum.
3. Gradually close the hot tap and check that the burner
pressure decreases to its minimum. Fully open the tap and
check that the burner pressure increases. Close the tap and
check that the burner goes off.
The burner pressure settings have been factory set and do
not require adjusting. If incorrect, check that the inlet gas
pressure is 20 mbar. If the inlet gas pressure is not 20 mbar,
either the pipework is too small or the gas supply to the
house is insufficient, in which case contact your gas supplier.
Central heating mode
1. Set the selector switch to (DHW and CH).
2. The burner will light at the ignition rate and will increase to the factory pre-set maximum output.
3. Turn off the boiler. Disconnect the pressure gauge and tighten the test point screw.
Test for gas soundness using suitable leak detection fluid.
Note: Refer to Technical Data, section 2.1 for burner pressure settings.
Alpha 240XP and 240XE - Commissioning
Burner pressure
test point
Inlet gas pressure
test point
Fig. 17