Ferroli F24 Installation, Servicing And User Instructions Manual page 13

Ferroli F24
3.02 Restrictor
For boiler operation, the restrictor supplied with the unit must be mounted following the instructions below.
Determine the correct size of flue restrictor required. Before inserting the flue gas duct in the boiler, check that
the restrictor fitted is correct and that it is correctly positioned (see fig. 14).
CHOICE OF RESTRICTOR:
• With 2 pipe system:
- Calculate the total flow resistance of the air and
flue pipes in metres (cap. 3.04.2)
- utilise the table shown below to choose the more
suitable restrictor for the flow resistance calculated
RESTRICTOR FOR TWO PIPE SYSTEM
Total flow resistance
of flue system
minimum maximum
0 m
13 m
23 m
38 m
Use
restrictor
size
mm
13 m 45
23 m 47
38 m 50
48 m No restrictor
N.B.: the diameter of the hole is
Fig. 14
• With concentric systems:
- Choose correct restrictor from table below.
RESTRICTOR FOR CONCENTRIC SYSTEM
Flue lenght up to:
1 bend + 1 meter
Ccncentric
60 / 100
1 bend + 3 meters No restrictor
1 bend + 3 meters
Ccncentric
1 bend + 4 meters
80 / 125
1 bend + 5 meters No restrictor
stamped on the restrictor
No restrictor is required for
back outlet fl ue
Use
restrictor
size
50 mm
45 mm
50 mm
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