INSTALLATION AND USE MANUAL
Chapter 2
page
12
Theoretical notions for installation
Technical service – MCZ GROUP S.p.A. all rights reserved - Reproduction prohibited
2.6.
COWL
If underestimated, it is a severe impediment to correct "chimney
system" operations.
Flue pipe draught also depends on its cowl.
Therefore, if hand made, its four exhaust sections must correspond to
more than twice the internal section of the flue pipe.
Having to exceed the peak of the roof, the cowl will be exposed
to wind, therefore an industrial type is recommended.
The cowl must meet the following requisites:
It must have an internal section equal to that of the chimney.
It must have a useful output section not less that double that
of the internal section of the flue pipe.
It must be built to prevent rain, snow and any foreign objects
from getting into the flue pipe.
They must be installed to guarantee adequate smoke
dispersion and out of the reflux area where negative pressure
forms.
For paired flue pipes, the cowl for solid combustion
and the one for the upper floor must be at least 50cm
higher than the other to avoid pressure transfers
between paired flues.
The cowl must not have obstacles within 10 m such as
walls, roof slopes and trees. Otherwise, raise it at least
1 m over the obstacle and, in the event of other nearby
cowls, keep them at least 2 m away. In any case, the
cowl must exceed the peak of the roof by at least 1m.
An industrial cowl,
with prefabricated
sections fitting
together, allows
optimal disposal of
the flue gases.
A
traditional
handmade
cowl.
The right exhaust
section must be at
least
twice
the
internal section of
the flue pipe, 2.5
times is ideal.
Steel cowl for flue pipe
with internal smoke
deflector cone.
1
m
t
0,
5
m
t