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AST 14 C 258/00
4.2 CHIMNEY SWEEP FUNCTION
The boiler features a flue cleaning function which must be used to measure
combustion efficiency during operation and to set the burner.
This function can be enabled only in the H DOMESTIC HOT WATER operating
mode. To enable it, press keys “info” and “reset” at the same time, and keep them
pressed for three seconds. Now the boiler performs the ignition sequence and then
operates at the burner maximum output fixed by the parameter P4.
The display shows the fan current rpm (number of revolutions per minute), the flow
temperature, the lit flame symbol with burner on, and the “broom” symbol to indicate that
the flue cleaning function is active.
By pressing the DHW “+” or “-” keys it is possible to change the fan speed from P5
(minimum speed) to P4 (maximum speed). In this case the display shows the wrench
symbol (parameter editing indicator) as well as the Hertz (H) number corresponding to the
fan speed.
This operation is useful when setting the combustion to the minimum output by gradually
pressing the DHW “-” key to pass to the fan minimum values. Following are the minimum
power values:
12 kW
24 kW
28 kW
39 Hz
42 Hz
40 Hz
Release the DHW “+” or “-” keys to go back to the previous screen showing the fan rpm
and the flow temperature.
The burner is switched off when the temperature detected by the flow probe exceeds 90°C
and switched on again when reaching 70°C.
During such function the pump is powered, the three-way valve switches to the heating
position, and the multifunction relay is excited by parameter P17=1 (remote relay) or
P17=3 (heating relay).
The function stops automatically after 15 minutes, or by pressing the "reset" key, or setting
a mode different from the “DHW” one.
