A
B
D
60°
E
C
F
A
B
C
D
E
45°
F
14
2-INSTALLATION
ROOF AT 60° ROOF AT 45°
SIZING
The negative pressure (draught) of a flue also depends on its height. Check the negative pressure with the values indicated in the technical
specifications. The minimum height of the chimney is 3.5 metres.
The interior cross-section of the flue can be round (best solution), square or rectangular (the ratio between the internal sides must be
≤1.5) with the sides joined with a minimum radius of 20 mm. The dimension of the cross-section must be
minimum Ø100mm.
The cross sections/lengths of chimneys must be correctly sized in accordance with the general method of calculation of UNI EN13384-1 or
other proven efficiency methods.
Some examples of flues available on the market are provided below:
AISI 316 steel chimney with
double chamber insulated with
ceramic fibre or equivalent
resistant up to 400°C.
Refractory chimney with
double insulated chamber and
external lightweight concrete
cladding with cellular material
such as clay.
Traditional square-section clay
chimney with insulating empty
inserts.
Avoid products with an internal
rectangular section where the
larger side is 1.5 times the
smaller side (e.g. 20x40 or
15x30).
EXCELLENT
GOOD
POOR
VERY POOR
A = MIN. 2.60 metres
B = DISTANCE > 1.20 metres
C = DISTANCE < 1.20 metres
D = 0.50 metres ABOVE HIGHEST POINT
E = 2.10 metres
F = REFLUX AREA
A = MIN. 2.00 metres
B = DISTANCE > 1.30 metres
C = DISTANCE < 1.30 metres
D = 0.50 metres ABOVE HIGHEST POINT
E = 1.50 metres
F = REFLUX AREA
FIGURE 5
FIGURE 6