Ferroli F24 Installation, Service And User Instructions Manual page 13

3.02 Restrictor
For boiler operation, the restrictor supplied with the unit must be mounted following the instructions below.
Determine the correct size of fl ue restrictor required. Before inserting the fl ue gas duct in the boiler, check that
the restrictor fi tted is correct and that it is correctly positioned (see fi g. 14).
Holes Ø : 45 47 50
• With 2 pipe system:
- Calculate the total fl ow resistance of the air and
fl ue pipes in metres (cap. 3.04.2)
- utilise the table shown below to choose the more
suitable restrictor for the fl ow resistance calculated
RESTRICTOR FOR TWO PIPE SYSTEM
Total flow resistance
of flue system
minimum maximum
0 m 13 m
13 m 23 m
23 m 38 m
38 m 48 m
Fig. 14
• With concentric systems:
Use
restrictor
size
mm
45
47
50
No restrictor
N.B.: the diameter of the hole is
stamped on the restrictor
No restrictor is required for
back outlet fl ue
- 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
Use
restrictor
size
50 mm
45 mm
50 mm
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