34
English
1.3 Chimney stack - Fig. 7 - 11
The flue must be fitted at the top with a device called a chimney stack,
designed to aid dispersion of the products of combustion in the
atmosphere.
The chimney stack must comply with the following requirements:
- it must have an internal section and shape the same as the flue;
- it must have a useful outlet section of not less than twice that of the flue;
- the part of the flue that emerges from the roof or remains in contact
with the outside (e.g. in the case of an open loft), must be covered
with brick or tile elements and well insulated. It must be built in such
a way as to prevent the penetration of rain, snow and foreign matter
into the flue and to ensure that in the event of winds from all
directions and angle, discharge of the combustion products is
assured (chimney stack with down-draught cowl);
- any buildings or other obstacles that are higher than the chimney
stack must not be too close to the actual stack Fig.9;
- the chimney stack must be positioned in such a way as to ensure
adequate dispersion and dilution of the products of combustion and
outside the reflux area. The size and shape of this area differ according
to the angle of inclination of the roof and it is therefore necessary to
adopt the minimum heights shown in Fig.10-11;
Example:
Check the slope of the roof (column
α
), and the
anticipated distance of the chimney stack from the axis of the ridge
(column
A
); if the distance is greater than “
A
” the height of the
chimney stack may be read in (column
H
); if the distance is less
than “
A
” the chimney stack must rise above the ridge by 0.5
metres.
6-8 m
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Fig. 9
FLAT ROOF
0.50 m
0.50 m
over 5 m
m or less
5 m
m or less
5 m
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Fig. 10
SLOPING ROOF
0.50 m above the ridge
height of reflux
area Z
ridge axis
distance more than A
α
H min.
distance
min. than A
Fig. 11
Pitch of the roof
Horizontal width of reflux
area from ridge axis
Minimun height of
outlet from roof
Height of reflux area
α
A
H minimo
Z
15°
1,85 m
1,00 m
0,50 m
30°
1,50 m
1,30 m
0,80 m
45°
1,30 m
2,00 m
1,50 m
60°
1,20 m
2,60 m
2,10 m
A
B*
* B equivale al
doppio di A
DT2030051-00
Fig. 7
A
B
B
DT2030191-00
Fig. 8
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