Cast iron fireplaces
22
Instructions for installation, use and maintenance – EN – Rev.07
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. Figure 5 gives some examples of
execution.
The minimum section must be 4 dm
2
(for example 20 x 20 cm) for devices whose duct diameter is
lower than 200 mm or 6.25 dm
2
(for example 25 x 25 cm) for devices 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 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.
Figure 5
(2) Representation of a correct flue with air-tight
door for the collection and discharge of solid
unburnt materials.
Figure 6
(1) The connection of more than one device to
the flue is not recommended.
Each device must have its own flue.
Figure 7
1) AISI 316 steel flue with double chamber insulated with material resistant to
400°C.
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.
A+1/2A
A
Max.
A+1/2A
(3)
(1)
(2)
(4)
NO
(1) Sportello
per
pulizia
SI
Door for
cleaning
YES
