4
Alpha CD25X/28X
The operating sequence of the boiler is controlled by the selector switch on the control panel. With the switch 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.
Setting the selector switch to position (2) the boiler will operate to provide central heating and hot water.
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.
If a clock is fitted to the boiler, it will only control the operating times of the central heating. Hot water will always be available
when a tap is opened.
When the selector is set to central heating and hot water, it will respond to a demand for heat in the following sequence:-
a. The pump will start, the fan will operate 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 50 seconds. The pump will continue to run for three
minutes.
d. When a hot tap is opened, the boiler automatically senses a flow of water. The pump will start, the fan will operate and
the main burner will light.
e. The boiler will continue to supply hot water at the temperature set by the thermostat until the tap is closed.
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.
Thermostatic or pressure equalising type -
When using these types of shower set the boiler domestic hot water
thermostat to maximum. The shower should then maintain a relatively constant temperature.
Manual bath mixer type shower -
When using this type of shower set the boiler domestic hot water thermostat to setting 7,
This should avoid excessive temperatures at the shower.
Note:
If you get unacceptable temperature variations with this type of shower, then a thermostatic or pressure equalising
type should be used.
5 BOILER OPERATION
6 HOT WATER USE
7 USING A SHOWER
