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Alpha HE CB/SY
The operating sequence of the boiler is controlled by the selector switch on the control panel. When the HE CB25/33 selector switch
is set to
(hot water only) the boiler will only operate to provide domestic hot water, ideal for Summer use when central heating
is not required.
With the selector switch set to position (2) the boiler will operate to provide central heating and for the HE CB25/33 hot water as
well.
HE CB25/33 only - If the boiler is operating to provide central heating and a hot water tap is opened, the boiler will automatically
switch over to provide hot water. Such an interruption in the central heating should not generally be noticed by any reduction in room
temperature.
Note: If a clock is fitted to the HE CB25/33 boiler, it will only control the operating times of the central heating. Hot water will
always be available when a tap is opened. If a two channel clock is fitted to the HE SY25 boiler it will control the operating times
of the central heating and hot water.
When the selector is set to position (2), it will respond to a demand for heat in the following sequence:-
a. The pump will start, the fan will operate at full speed and the main burner will light.
b. The output of the burner is automatically controlled to suit the system demand.
c. When the temperature of the system water in the boiler reaches that set by the thermostat or the room thermostat is
satisfied, the main burner is turned off and the fan stops after 20 seconds. The pump will continue to run to remove any
residual heat from the boiler.
d. HE CB25/33 only - When a hot tap is opened, the boiler automatically senses a flow of water. The pump will start, the fan
will operate at full speed and the main burner will light.
e. HE CB25/33 only - The boiler will continue to supply hot water at the temperature set by the thermostat until the tap is closed.
5 BOILER OPERATION
6 HOT WATER USE - HE CB25/33 only
4 LIGHTING INSTRUCTIONS
Refer to Fig. 1a or 1b for boiler controls.
1. Ensure the following:-
a. Electrical supply to the boiler is off.
b. All heating controls and thermostats are set to OFF or minimum position.
c. All isolation valves at the bottom of the boiler are in the open position (slot on the spindle in line with the valves i.e.
).
d. The gas and water supplies are on at the mains.
e. The heating system pressure is within the green band as shown by the pressure gauge.
2. Switch on the electrical supply to the boiler.
3. Set any room thermostats to maximum and ensure that any clock is in an 'on' position.
4. HE CB25/33 only - Set the selector switch to
(hot water only).
5. HE CB25/33 only - Turn the hot water thermostat fully clockwise. 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.
6. Set the selector switch to position (2) and turn the heating thermostat fully clockwise, refer to Section 3.1. The main burner
will light and the boiler will provide central heating.
7. Set the boiler thermostats, clock, external controls i.e. room thermostat to your chosen settings and the boiler is ready to operate.
To turn the central heating off i.e. in Summer:- Set the selector switch to position (1).
To turn the boiler off for short periods:- Set the selector switch to position (1).
Note: In this position the pump will automatically operate for 5 minutes in every 24 hours. If the water temperature falls below
8°C the built-in frost thermostat will operate the boiler automatically until the temperature of the water in the heating system has
been raised.
To turn the boiler off for longer periods:- Switch off the electrical supply to the boiler. If required, all supplies i.e. gas, water
and electricity may be turned off at the mains. If there is any possibility of the boiler being left during frost conditions, then the
boiler and system should be drained and a label attached to the boiler drawing attention that the system has been drained. If
this is required, contact your Service Engineer.
The supply of hot water is almost instantaneous at the boiler, but the time taken to reach a tap and the temperature at which it leaves
the tap will depend on the rate at which the water is drawn off and the length of the pipe between the tap and the boiler.
Fully opening a hot tap may not always provide the maximum temperature as the flow rate may be too high, try closing it slightly
until the maximum temperature is achieved.
Depending on your mains water pressure, it may not be possible to operate several hot taps at the same time.