________________________________________________________________________________
72
AST 14 C 258/00
For a correct operation of the boiler, the minimum flow rates must comply with the values
specified below:
Power
Flue gas
side
modules
Water side
modules
Water flow rate
to be ensured
[kW]
[l/h]
24Kw 3+1 2+2
400
28 kW
4+1
3+2
600
The check is based on the difference (
∆
T) between the flow temperature and the return
one according to the fan power. If such difference exceeds the minimum allowed threshold
the burner enters in shutdown.
There are triggering thresholds at different rates that progressively reduce the burner
operation time at specific switching on/off time.
The intermittence time (ON-OFF) activated during the heating, anti-freeze or flue cleaning
requests, are different from those activated during the plate DHW or water heater modes.
Following is an overview of the different situations:
Power
Type of
request
Limit water flow
rate
Burner ON
time
Burner OFF
time
Error
[kW]
[l/h]
[min] [min]
24 kW
Heating, anti-
freeze, flue
cleaning
367
3 1
E81
333
2 2
E82
300
1 3
E83
Plate DHW,
boiler
367
3 5
E81
333
2 5
E82
300
1 5
E83
28 kW
Heating, anti-
freeze, flue
cleaning
550
3 1
E81
500
2 2
E82
450
1 3
E83
Plate DHW,
boiler
550
3 5
E81
500
2 5
E82
450
1 5
E83
The burner is completely switched off (0 min ON) if in the worst case (300 or 450 l/h) the
flow and return temperature derivative values are both lower than 0.5°C/sec. In this case
the reference error is E84.
Warning: E81, 82, 83 and 84 errors are not indicated on the boiler display by default. To
display them it is necessary to set the parameter P90=1, and the fault can be reset by the
user by means of the "reset" key.
During the water flow checks and the relevant burner switching on and off operations, the
pump remains always powered.
