LA NORDICA ROSSELLA PLUS Instructions Pour L'installation, L'utilisation Et L'entretien page 19

Rossella Plus – Rossella Plus forno / Nicoletta – Nicoletta forno / Gisella
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
for devices whose duct diameter is lower than 200 mm or 6.25
dm (for example 25 x 25 cm) for devices with diameter greater
2
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.
7192450 – EN
(for example 20 x 20 cm)
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) (2)
(3) (4)
Max.
A+1/2A
(1) AISI 316 steel flue with double
chamber insulated with material
resistant to 400° C.
100% excellent.
(2) Refractory flue with
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.
(3)
Chimney cap for steel
flue with internal cone
deflector of smokes.
A+1/2A
A
Efficiency
double
Picture 3
Picture 4
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