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6. FLUE
Essential requirements for correct appliance operation:
• the internal section must preferably be circular;
• the appliance must be thermally insulated and impermeable and built with suitable materials which are resistant to heat, combustion
products and any condensation;
• there must be no narrowing and vertical passages with deviations must not be greater than 45°;
• if already used, it must be clean;
• the technical data from the instruction manual must be respected;
If the flues are of a square or rectangular section, the internal edges must be rounded with a radius of not less than 20 mm.
For the rectangular section, the maximum ratio between the sides must be ≤ 1.5.
A section which is too small causes a reduction in draught. A minimum height of 4 m is advisable.
The following materials are
FORBIDDEN
and compromise the good operation of the appliance: asbestos cement, galvanised steel, rough
shows some example solutions.
The minimum section must be 4 dm
2
(for example 20x20 cm) for appliances whose pipe dimensions are less than 200 mm, or 6.25
dm
2
(for example 25x25 cm) for appliances with a diameter of more than 200 mm
.
The draught created by your flue must be sufficient but not excessive.
A section of the flue which is too large can present a volume which is too large to heat and therefore cause operating difficulties for the
appliance; to avoid this, it is necessary to intubate the appliance for its entire height. A section which is too small causes a reduction in
draught.
The flue must be at a suitably distance from flammable or combustible material using suitable insulation or an air space.
It is
FORBIDDEN
to pass system piping or air ducts inside the flue. It is also forbidden to create moveable or fixed openings on the flue
itself, for the connection of further different appliances (See chapter CONNECTING A FIREPLACE OR OPEN HEARTH TO THE FLUE).
6.1. CHIMNEY POT
The flue draught depends on the suitability of the chimney pot.
It is therefore essential that, if built in a handcrafted way, the exit section is more than twice the internal section of the flue
) .
As it must always go past the ridge of the roof, the chimney pot must ensure exhaust even in the presence of wind (
The chimney pot must meet the following requirements:
• Have an internal section equivalent to that of the chimney.
• Have a useful exit section of double the internal section of the flue.
• Be built so as to prevent rain, snow or any foreign body entering the flue.
• Be easy to inspect, for any maintenance and cleaning operations.
6.2. CONNECTION TO THE CHIMNEY
Products with automatic door closing (type 1) must operate, for safety reasons, with the furnace door closed (except during the fuel loading
or ash removal phases).
Products with non-automatic door closing (type 2) must be connected to their own flue.
Operation with doors open is only allowed when supervised.
The connection pipe to the flue must be as short as possible, straight horizontal and positioned slightly in ascent, and watertight.
Connection must be carried out with stable and robust pipes (we recommend a thickness of 2 mm) and be hermetically secured to the flue.
The internal diameter of the connection pipe must correspond to the external diameter of the cooker flue gas exhaust stub pipe (DIN 1298).
ATTENTION
: as far as concern the realisation of the flue connection and flammable materials please follow the requirements provided by
UNI 10683 standard. The flue must be properly spaced from any flammable materials or fuels through a proper insulation or an air cavity.
IMPORTANT: the unused flue gas exhaust hole must be covered with its respective cap
(See chapter: DIMENSIONS).
The chimney pressure (DRAUGHT) must be at least 17-20 Pascal (=1.7-2 mm of water column). The measurement must always be carried
out when the appliance is hot (nominal calorific power). When the pressure exceeds 20 Pascal, it is necessary to reduce it through the
installation of an additional draught regulator (false air valve) on the exhaust pipe or in the chimney, according to the regulations in force.
For correct appliance operation, it is essential that sufficient air for combustion is introduced into the place of installation (see paragraph
6.3. CONNECTING A FIREPLACE OR OPEN HEARTH TO THE FLUE
The flue gas channel is the stretch of piping which connects the thermo-product to the flue. In the connection, these simple but extremely
important principles must be respected:
• under no circumstances use a flue gas channel with a diameter less than that of the exhaust clamp with which the thermo-product is
equipped;
• each metre of the horizontal stretch of the flue gas channel causes a slight loss of head which must be compensated if necessary by
elevating the flue;
• the horizontal stretch must never exceed 2 metres (UNI 10683);
• each bend of the flue gas channel slightly reduces the flue draught which must be compensated if necessary by elevating it suitably;
• The UNI 10683 – ITALY regulation requires that under no circumstances must there be more than 2 bends or variations in direction
including the intake into the flue.
If the user wishes to use the flue as a fireplace or open hearth, it is necessary to seal the hood below the entrance point of the flue gas
channel pos.
A
.
If the flue is then too big (e.g. 30x40cm or 40x50cm), it is necessary to intubate it with a stainless steel tube with a diameter of at least
200mm, pos.
B
, taking care to close the remaining spaces between the pipe and the flue immediately under the chimney pot pos.
C
.
