Technical data

25
5.4 INITIAL LIGHTING - Refer to Fig. 26
1. Before turning on the gas and electrical supplies check the heating system is filled to the correct pressure. Refer to
Section 5.1 Fill the System. The pressure gauge on the right of the control panel indicates the heating system pressure.
When the boiler is cold the needle should be within the green band.
2. With the gas and electrical supplies to the boiler off, ensure that the central heating flow and return valves are open.
3. Turn on the gas and electrical supplies to the boiler.
When the electricity supply is turned on, the boiler will automatically go through a system purging cycle for 8 minutes
counting down from 96 on the display. This can be interrupted by pressing the RESET button (item 3 in Fig. 26). It is
recommended that this cycle is allowed to complete when first lighting the boiler to help remove air from the system.
After this the boiler will be in either Standby or On mode, the On-Off/Standby button (item 1 in Fig. 26) is used to scroll
between these modes or press and hold it in to turn the boiler off.
Note: This does not isolate the electricity supply to the boiler.
4. Ensure all external controls are calling for heat.
If the optional controls are fitted, refer to the instructions supplied, and ensure they are in an 'on' mode.
5. Press the Summer/Winter button (item 2 in Fig. 26) to select either summer (
) or winter ( ) mode.
Note: The Summer mode will only function if the Alpha System Diverter valve kit has been fitted.
When using a standard Y or S plan system the boiler MUST be left in the Winter mode.
Summer (
): In this mode the boiler will only fire when hot water is requested to heat the hot water cylinder. The
heating will not function even if requested by any controls. The desired hot water temperature can be set using the hot
water selector switch (item 5 in Fig. 26) on the control panel, when the boiler operates the display will indicate the actual
primary flow temperature (item 14 in Fig. 26).
Winter (
): In this mode the boiler will provide heating and heat the DHW cylinder depending on the request from any
controls fitted. The boiler will always prioritise hot water to the domestic hot water cylinder when it requires heating. The
heating will activate depending on the request from any external controls fitted.
The domestic hot water (item 5 in Fig. 26) and central heating (item 6 in Fig. 26) selector switches on the control panel
can then be turned to the required set temperatures shown on the display, (item 5 in Fig. 26 is only operational if the
Alpha Diverter valve kit has been fitted). The display will then display the actual primary flow temperature (item 14 in
Fig. 26) when operating in heating or to heat the DHW cylinder.
Note: If a weather compensation probe is fitted (can only be fitted when the Alpha Diverter valve kit is fitted) a gradient
value of 1 to 9 is displayed when adjusting the central heating temperature selector switch. This is because the boiler
output is modulated according to outside temperature. Refer to external probe instructions for further information on this
feature.
6. From this moment the boiler functions automatically. With no demand for heat (central heating or domestic hot water
production) the boiler goes to “standby” function.
Each time the burner ignites, the flame present symbol (item 10 in Fig. 26) is displayed together with the relative
strength of the flame.
For any controls fitted please refer to the instructions supplied with the controls for connection and operation details.
5.5 BOILER OPERATION
If there is a call for heat, the pump will start to circulate the central heating water. The fan will run and the pre-mix burner will
light. The burner output then automatically adjusts to suit the system demand; as the temperature of the water in the boiler
approaches that set by the adjustable temperature thermostat, the burner output is reduced. When the set temperature is
reached, the burner is turned off. The fan continues to run for 30 seconds and the pump continues to run for three minutes,
after which the burner can relight if required. If the primary sensor has not registered the pre-set temperature but the room
thermostat is satisfied the burner is turned off. The fan continues to run for 30 seconds and the pump continues to run for 10
seconds. In this instance there is no delay before the burner will relight.
If there is a request to heat the DHW cylinder during the burner delay, the boiler will operate to heat the cylinder until the
demand is satisfied; the boiler will then immediately revert to provide CH if there is a demand.
Note: If the system pressure is very low, the primary pressure switch will prevent the boiler from operating.
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 4°C, providing the electrical supply is on and the boiler is in standby mode. The boiler will operate until the water
temperature in the boiler reaches 42°C.
Any other pipework outside of the boiler must be protected from the risk of freezing and insulated. Additional protection from
an external frost thermostat and pipe thermostats should be considered.
Pump Cycle
If the electrical supply is on and the boiler has not operated for 24 hours in heating or hot water, the pump will operate
automatically for thirty seconds every 24 hours.
Alpha InTec S - Commissioning