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5.5 BOILER OPERATION
With the optional Alpha Diverter Kit fitted, the E-Tec S operates with hot water priority. If the heating is on and there is a hot
water demand the valve will divert the primary hot water to the cylinder until the cylinder sensor is satisfied. The heating will
be held off during this period so it is recommended that a high recovery cylinder is used. The kit comprises of a diverter valve
and cylinder sensor.
Central Heating Mode
If there is a call for heat, the pump will start to circulate the central heating water. The fan will run and the premix 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 preset 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.
Note: If the system pressure is very low, the primary pressure switch will prevent the boiler from operating.
The fan modulates according to the output required.
Frost Thermostat
The boiler incorporates a built in frost thermostat which automatically turns on the boiler 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.
5.6 CHECKING THE COMBUSTION - CHIMNEY SWEEP MODE
As part of the Benchmark Checklist procedure the combustion levels of the boiler when the installation is completed must be
measured and recorded.
The air gas ratio of the boiler has been factory-set and should not require adjusting during commissioning. If adjustment is
recommended or required the engineer must be competent to carry out this work. See Fig. 5.3 for analyser test point.
If the boiler requires adjusting or setting to operate on LPG, further guidance is detailed in Section 5.11.
Chimney Sweep Mode
Without any CH or DHW demand, press and hold the reset button for eight seconds and the boiler will fire at a fixed output.
The parasol and snowman (
) will flash at the same time to indicate this mode, if a Climatic controller is fitted it will
display ERR>07 code on the controller (this is not a fault).
Using the DHW up and down buttons you can change between three predefined output levels:
• 0% (low fire)
• 80 - 90% (Max CH output) Note: CO
2 testing at this output is not required - % output depends on model and gas type
• 99% (Max DHW output)
This mode will remain active for fifteen minutes or can be cancelled by turning the boiler off.
Use the DHW down button to set the output to minimum to check the minimum CO
2 reading, wait for the boiler stabilise,
check the combustion and record the reading.
Use the DHW up button to set the output to maximum to check the maximum heating CO2, again allow the burner to
stabalise and record the reading.
If the CO
2 readings are not within the stated tolerance (refer to Section 2.1) then check the installation including the complete
flue assembly and repeat the above process.
The CH up and down buttons can be used to increase and decrease the output in incremental steps if required.
When checking at maximum output the boiler will have a higher noise level, this is normal.
Alpha E-Tec S 20 and 30 - Commissioning
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