Ferroli TEMPRA 30 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. 11).
Holes Ø : 45 47 50
CHOICE OF RESTRICTOR:
• 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
15 m
30 m
40 m
Use
restrictor
size
mm
15 m 47
30 m 50
40 m 52
45 m No restrictor
TEMPRA 30
N.B.: the diameter of the hole is
Fig. 11
• With concentric systems:
- Choose correct restrictor from table below.
RESTRICTOR FOR CONCENTRIC SYSTEM
Flue lenght up to:
1 bend + 1 meter
Concentric
60 / 100
1 bend + 3 meters
1 bend + 3 meters
Concentric
1 bend + 4 meters
80 / 125
1 bend + 5 meters
stamped on the restrictor
Boiler is fitted with Ø47
restrictor as standard
Use
restrictor
size
52 mm
No restrictor
50 mm
No restrictor
13