Ferroli PREXTHERM N 400 Instructions Pour L'installation Et L'entretien page 8

3.4 Maintenance
To ensure the maximum reliability of the heating system and minimum running costs, the boiler must be cleaned regularly, at least once a year.
These maintenance operations must be performed by qualified and specialist personnel.
In any case, it is good practice to check the condition inside the boiler once a week, by opening the front door, so as to avoid anomalous
operation for extended periods. During this operation, all the turbulators should be removed longitudinally, so as to prevent them from
becoming clogged due to the inevitable deposits of soot.
Cleaning the boiler
1 Disconnect the power supply to the boiler
3 Open the door by undoing the 2 nuts (see 2.6).
4 Carefully clean the tube bundle: open the front door of the boiler completely, and remove all the turbulators from the tubes. Thoroughly
clean the tube bundle using the brush. Remove the soot deposits from the rear smokebox, through the door. Brush and scrape the furnace
to remove the deposits of sulphur and other solid substances. Check the nozzles and the position of the burner combustion head, in the
event where carbon deposits are formed (to clean the burner, always refer to the instructions provided by the manufacturer).
5 Close the door again, and fasten it using the knob.
Descaling the boiler
It is extremely important, above all in areas where the water is very hard, to periodically de-scale, or better still, to inhibit the formation of lime-
scale deposits in the system. These periodical or continuous operations are indispensable for extending the life of the boiler and preventing
localised overheating of the metal plate, differential expansion or thermal shock. Therefore, after the first operating season at the latest,
thorough descaling should be performed This operation must be repeated at the end of the heating period. If continuous descaling is practiced,
it is essential to use a safe and absolutely non-corrosive product. In addition, it is essential to periodically remove the slime that deposits inside
the boiler, through the special fitting.
4. TECHNICAL SPECIFICATIONS
Prextherm N 400
Prextherm N 500
Combustion chamber
Model Ø
mm
Prextherm N 400 518
Prextherm N 500 518
8
Heat input
gas+oil (NHV)
kW
Model
Max Min
435 279
541 345
Combustion
chamber
load loss
Lenght Volume
∆p mbar
mm m3
1525 0,32 2,5
1705 0,36 2,9
Heat
Water Operating
output
content pressure
kW
Max Min dm3
400 260 460
500 325 518
Dimensions
A B C Ø1
mm mm mm mm
1675 610 1662 DN80 - 3"
1875 810 1862 DN80 - 3"
PREXTHERM N
Water
Boiler weight
with no load
pressure drop
∆t 10°C ∆t 20°C
∆p mbar ∆p mbar
bar
6 14 7
6 18 9
Connections
Ø2
mm Ø3 Ø4
DN80 - 3" 1" 1/2 3/8"
DN80 - 3" 1" 1/2 3/8"
Kg
780
850
Ø5
1"
1"
fig. 5