Flue; Chimney Cap Position - LA NORDICA ROSA Aufstell- Und Bedienungsanleitung

5.

FLUE

Essential requirements for a correct operation of the device:
• the internal section must be preferably circular;
• be thermally insulated and water-proof and produced with materials
suitable to resist to heat, combustion products and possible
condensates;
• not be throttled and show a vertical arrangement with deviations not
greater than 45° ;
• if already used, it must be clean;
• 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
devices whose duct diameter is lower than 200 mm or 6.25 dm
(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.
(1)
Industrial chimney
cap with pre-fabricated
elements – it allows an
excellent discharge of the
smokes.
20
(for example 20 x 20 cm) for
2
(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).
(1)
(3)
(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.
2
(4) Avoid flues with rectangular internal
section whose ratio differs from the
drawing. Efficiency 40% poor.
(3) Chimney cap for
steel flue with conical
deflector of smokes
ROSA - ROSETTA
(2)
(4)
A+1/2A
Max.
A+1/2A
A
Picture 3
Picture 4
1095080 – Rev.05 – EN