Ferroli DOMINA 102 DGT Installation, Servicing 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 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. 13).
Holes Ø: 47 50 52
Choice of restrictor:
• With concentric pipes:
• With 2 pipe system:
DOMINA 102 DGT
Fig. 13
- up to 1m long + one bend, use the 52 mm restrictor.
- for flue lengths over 1 metre, use no restrictor.
- 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
ON DOMINA 102 DGT
Total flow resistance
of flue system
minimum
0 m
20 m
35 m
45 m
N.B.: the diameter of the hole is stamped
on the restrictor
No restrictor is required for back
outlet flue
Use
restrictor
size
maximum mm
20 m 47
35 m 50
45 m 52
50 m no restrictor
13