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27
AST 14 C 258/00
MODULATING FAN
The fan ensures a constant air flow during the modulation range from the maximum to the
minimum heat capacity.
The fan speed changes according to the modulation power provided by the board as well
as the type of boiler specified in the chart below.
This speed variation is due to the heat request and the temperature detected by the DHW
and heating NTC probes.
Once the ignition power values and the maximum and minimum power have been set, the
modulation range between the minimum and maximum values.
FAN SETTINGS
PARAMETERS
12 kW
natural
gas
12 kW
propane
24 kW
natural
gas
24 kW
propane
28 kW
natural
gas
28 kW
propane
P0
Model type
0 5 1 3 2 4
P4
Fan speed at maximum output
(DHW)
187 Hz 181
Hz 199
Hz 192
Hz 201
Hz 198
Hz
P5
Fan speed at minimum output
(DHW and heating)
39 Hz 39
Hz 42
Hz 42
Hz 40
Hz 40
Hz
P6
Fan speed at ignition output
48 Hz
48 Hz
58 Hz
58 Hz 60
Hz 60
Hz
P7
Heating maximum power upper
limit
75 % 75
% 88
% 88
% 88
% 88
%
P8
Start of negative ramp descent
56 Hz
56 Hz
56 Hz
56 Hz 60
Hz 60
Hz
P9
Negative ramp duration
(sec x 10)
18
18
18
18
25
25
The fan is powered with 230 Vac; to change its speed the board sends another voltage
signal (PWM). A HALL sensor integrated in the fan checks the consistency between the
speed required by the board and the actual one.
The Hall sensor is a magnetostrictive sensor that sends a PWM signal back; the electronic
board constantly checks the consistency between the signal sent by the fan and that of the
Hall sensor, and if they do not match the boiler stops generating an error code linked with
the fan fault (E40).