CLASSICA 350 – 450
18
1590001
– EN
•
observe the technical data of the instructions manual;
Should the flues have a square or rectangular section, internal edges must be rounded with a radius not lower than 20
mm. For the rectangular section, the maximum ratio between the sides must be
≤
1.5.
A too small section causes a decrease of the draught. It is
suggested a minimum height of 4 m.
The following features
are forbidden
and therefore they
endanger the good operation of the device: asbestos cement,
galvanized steel, rough and porous internal surfaces. Picture 3
gives some examples of execution.
The minimum section must be 4 dm
2
(for example 20 x 20
cm) for devices whose duct diameter is lower than 200 mm
or 6.25 dm
2
(for example 25 x 25 cm) for devices with
diameter greater than 200 mm.
The draught created by the flue must be sufficient, but not
excessive. A too big flue section can feature a too big volume
to be heated and consequently cause difficulties in the
operation of the device; to avoid this, tube the flue along its
whole height. A too small section causes a decrease of the
draught.
The flue must be properly spaced from any flammable
materials or fuels through a proper insulation or an air
cavity.
It is forbidden to let plant piping or air feeding channels pass in
the same flue. Moreover, it is forbidden to create movable or
fixed openings on the same for the connection of further other
devices.
5.1. CHIMNEY CAP POSITION
The draught of the flue depends also on the suitability of the chimney cap.
Therefore, if it is handicraft constructed, the output section must be more than twice as big as the internal section of
the flue.
Should it be necessary to exceed the ridge of the roof, the chimney cap must assure the discharge also in case of
windy weather (Picture 4).
The chimney cap must meet the following requirements:
•
have internal section equivalent to that of the stack.
•
have a useful output section twice as big as the flue internal one.
•
be manufactured in such a way as to prevent the penetration of rain, snow, and any other foreign body in the flue.
•
be easily checkable, for any possible maintenance and cleaning operation.
Picture 3
Picture 4
(1) AISI 316 steel flue with double chamber
insulated with material resistant to 400°C.
Efficiency 100% excellent.
(2) Refractory flue with double insulated chamber
and external coating in lightweight concrete.
Efficiency 100% excellent.
(3) Traditional clay flue square section with
cavities.
Efficiency 80% excellent.
(4) Avoid flues with rectangular internal section
whose ratio differs from the drawing.
Efficiency
40% poor.
A+1/2A
A
Max.
A+1/2A
(3)
(1)
(2)
(4)
(1)
Industrial chimney
cap with pre-fabricated
elements – it allows an
excellent discharge of the
smokes.
(2)
Handicraft chimney
cap. The right output
section must be at least
twice as big as the
internal section of the flue
(ideal value: 2.5 times).
(3)
Chimney cap for steel
flue with internal cone
deflector of smokes.
