Flue; Chimney Cap - Nordica FULVIA Instructions Pour L'installation, L'utilisation Et L'entretien

FULVIA – GAIA
5.

FLUE

Essential requirements for a correct operation of the
appliance:
•
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 appliance: asbestos
cement, galvanized steel, rough and porous internal
surfaces. Picture 3 gives some examples of execution.
The minimum section must be 4 dm
20 cm's) for appliances whose duct diameter is lower
than 200 mm, or 6.25 dm
appliances 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 appliance; 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 appliances.

5.1. CHIMNEY CAP

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.
7191010 – EN
2
(for example 20 x
2
(for example 25 x 25 cm's) for
(1) (2)
(3) (4)
(1) AISI 316 steel flue with double chamber
insulated with material
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.
Picture 3
A+1/2A
Max.
A+1/2A
A
resistant to 400° C.
19