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8.7. The chimney flue
In addition to the general requirements applicable to the smoke duct and to the chimney flue, the chimney flue:
Must only be used to discharge smoke.
Must be correctly sized to meet smoke evacuation requirements (EN 13384-1 non-exhaustive example)
Is preferably insulated, made of steel and with a circular inner cross-section. If rectangular, the edges must
normally have a radius of not less than 20 mm and a ratio between internal dimensions <1.5.
Normally have a minimum height of 1.5 metres.
Maintain a constant cross-section.
Be waterproof and thermally insulated to ensure draught.
Preferably have a collection chamber for unburnt material and any condensation.
If pre-existing, it must be cleaned, to avoid fire hazards.
As a general guideline, it is advisable to duct the chimney flue if its diameter is greater than 150 mm, the
assessment of which is the responsibility of the technician in charge of sizing the system.
8.8. Ducted system
In addition to the general requirements applicable to the smoke duct and to the chimney flue, the ducted system:
Must operate under negative pressure.
Must be inspectable.
Must comply with local regulations.
8.9. The chimney pot
Must be windproof.
Must have an inner cross-section equivalent to that of the chimney flue and an outlet smoke passage cross-
section equal to at least twice the inner cross-section of the chimney flue.
In the case of paired chimney flues (which should be at least 2 m apart), the chimney pot that receives the solid
fuel product discharge or that of the highest floor must be at least 50 cm above the other.
Must go beyond the reflux area (in Italy, refer to Standard UNI 10683)
Must allow for maintenance operations to be performed on the chimney
8.10. Air intake for combustion
8.10.1. Direct air intake
The watertight product is suitable for a watertight installation. In this case the air intake must be a direct air intake,
connected in a watertight manner.
Install an air intake with a net superficial section (regardless of nets or other protections) equal to at least the section
of the air intake hole behind the product.
Determine the diameter according to pressure loss.
Connect the air intake to the hole also with a flexible pipe.
Increase the pipe diameter if the pipe is not smooth: determine the pressure loss.
We recommend not exceeding 4 m and not using more than 2 curves, considering the draught of the smoke outlet.
8.10.2. Indirect air intake
If the use of a watertight product is not required, it is possible (although not recommended) the execution of an
indirect air intake
Install an air intake at the pavement level with a net section area (regardless of nets or other protections) equal to at
least 80 cm2 (diameter 10 cm).
To avoid air currents we recommend the installation of an air intake behind the product or behind a radiator.
We do not recommend the installation in front of the product to avoid inconvenient air currents.
