Technical data

19
Alpha 500E - Commissioning/Boiler Operation
5.8 USER INFORMATION
The User must be advised (and demonstrated if necessary) of the following important points:-
1. How to light and turn off the boiler and how to operate the system controls.
2. The importance of annual servicing of the boiler to ensure safe and efficient operation.
3. That any servicing or replacement of parts must only be carried out by CORGI registered personnel.
4. Ensure that the boiler controls and room thermostat (if fitted) are set to the User's requirements.
5. Tell the User about the sealed system pressure.
6. Tell the User that if the electrical supply neon is illuminated and the boiler has not operated for 24 hours for heating or
hot water, the pump will automatically operate for 5 minutes.
7. Explain to the User that an internal frost thermostat is fitted in the boiler, and that electrical supply to the boiler must be left
on (electrical supply neon illuminated) for the thermostat to operate.
8. Show the User the position of the pressure relief valve discharge pipes and tundish for the heating and DHW systems.
9. Hand the User's instructions and the Benchmark Log Book to the User.
10. Leave these Installation and Servicing instructions with the User for use on future calls.
6 BOILER OPERATION
The boiler operating mode is controlled by the selector switch on the facia panel. When set to , the boiler will only operate in
the Domestic Hot Water mode. When set to
, it will operate in the Domestic Hot Water and Central Heating mode.
Note: The clock (if fitted) only controls the operating times of the central heating, not domestic hot water - DHW is available
continuously.
Domestic hot water supply always takes priority over central heating. If a demand for hot water is required during a central
heating period, the boiler will automatically switch to the hot water mode until the demand is satisfied i.e. storage water is to the
required temperature. This interruption in the central heating is only when the demand for hot water is present and should not
be noticed by the User.
6.1 CENTRAL HEATING MODE
If there is a call for central heating the diverter valve is operated, the pump will start to circulate the primary heating water,
operating the flow switch. The fan will run at full speed; once the air pressure switch is proved the burner will light. The burner
output then automatically adjusts to suit the system demand; as the temperature of the heating water in the boiler approaches
that set by the adjustable central heating thermostat the burner output is reduced. When this set temperature is reached, the
burner is turned off and the fan stops. The pump continues to run for 3 minutes to remove residual heat build up in the boiler.
The burner will not relight for 3 minutes; unless there is a demand for domestic hot water during this delay.
In this instance, the boiler will operate to satisfy the domestic hot water demand and the boiler will then immediately revert to
provide central heating, if there is a demand.
6.2 DOMESTIC HOT WATER MODE
When there is a demand for hot water (temperature of stored hot water is below that set by the thermostat), the pump will start
to circulate the primary heating water, operating the flow switch. The fan will run at full speed; once the air pressure switch is
proved the burner will light. The burner output then automatically adjusts to suit the demand required to raise the temperature
of the domestic hot water within the store to the temperature set by the adjustable domestic hot water thermostat. When this set
temperature is reached the burner is turned off and the fan stops. The pump continues to run for 3 minutes to remove residual
heat build up in the boiler.
When the hot water demand has been satisfied, the 3-way diverter valve operates to divert the primary heating water to the
central heating, if there is a demand.
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 neon
is illuminated. The boiler will operate until the water temperature in the
system reaches approximately 30°C.
6.4 PUMP
If the electrical supply neon is illuminated 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.