19
6.2
DOMESTIC HOT WATER MODE
When a demand for hot water (by opening a hot tap, etc.) is sensed by the flow switch, the pump starts and the burner lights at
its middle output, increasing to its maximum output. Water in the boiler is then diverted from the central heating system to the
domestic hot water heat exchanger, heating the incoming mains water. The burner output is varied to maintain the temperature
of the hot water as that set by the adjustable temperature selector. When the flow switch senses that hot water is no longer
required the burner is turned off and the boiler immediately returns to the central heating mode.
In both modes the fan operates at full speed before the burner lights, remaining at that speed until the demand is satisfied.
6.3
FROST THERMOSTAT
The boiler incorporates a built in frost thermostat which automatically turns on the boiler and pump if the water in the boiler falls
below 5°C, providing the electrical supply is on, if applicable, the pilot is alight. The boiler will operate until the water
temperature in the system reaches approximately 30°C.
6.4
PUMP
If the electrical supply is on and the boiler has not operated for 24 hours for heating or hot water, the pump will operate
automatically for five minutes every 24 hours.
6.5
RESET BUTTON (240XE only)
When the reset button (
) is illuminated it indicates that the burner has failed to light - Press the reset button (see Fig. 16)
and the ignition sequence will restart.
6.6
OVERHEAT THERMOSTAT
When this thermostat operates on the Alpha 240XP the pilot is turned off and will have to be relit. When it operates on the
Alpha 240XE the boiler will not operate and the red button on the overheat thermostat must be pressed to reset it.
Alpha 240XP and 240XE - Boiler Operation/Routine Servicing
To ensure efficient operation of the boiler it is recommended that it is checked and serviced as necessary at regular intervals.
The frequency of servicing will depend upon the particular installation conditions and usage, but in general once per year
should be adequate.
It is the law that any service work must be carried out by a competent person, ie CORGI registered personnel.
7.1
IMPORTANT NOTES PRIOR TO SERVICING
1.
Check the flue terminal outside and ensure it is not blocked.
2.
Run the boiler and check the operation of its controls.
3.
Refer to Fig. 2 or 3 for location of flue sampling point.
4.
Ensure that all system connections and fittings are sound. Remake any joints and check the tightness of any fittings that
may be leaking.
5.
It is recommended that the operation of the safety valve is checked by turning the head anti-clockwise until it clicks. The
click is the safety valve lifting off its seat allowing water to escape from the system - check that this is actually happening.
6.
Refill, vent and re-pressurise the system as necessary. (Refer to Commissioning, section 5.1).
If the system pressure exceeds 2.5 bar when operating at maximum temperature, the heating expansion vessel should be
checked and re-pressurised, if necessary.
Note: 1. Check the expansion vessel charge only when the system pressure is zero.
2. The expansion vessel pressure test point is accessible from the top and rear of the boiler.
7.
Record details of the service in the Service History section on the back page of this manual.
Warning: Before servicing the boiler, isolate the electrical supply and close the boiler gas service cock. Allow the boiler to cool.
The data label is positioned on the left hand case side panel and is visible after removing the front casing.
Always test for gas soundness after servicing any gas carrying components.
7
ROUTINE SERVICING
Summary of Contents for Alpha 240XE
Page 35: ...35 Alpha 240XP and 240XE Wiring Diagrams 9 2 ILLUSTRATED WIRING DIAGRAM Alpha 240XE ...
Page 36: ...36 Alpha 240XP and 240XE Wiring Diagrams 9 3 FUNCTIONAL FLOW WIRING DIAGRAM Alpha 240XP ...
Page 37: ...37 Alpha 240XP and 240XE Wiring Diagrams 9 4 FUNCTIONAL FLOW WIRING DIAGRAM Alpha 240XE ...
