Immergas NIKE Mini 28 Manual De Instrucciones página 89

1.6 Chimneys/flues.
General. A chimney/flue for evacuating the combustion products of natural
draught boilers must:
- be sealed to prevent escape of combustion products, waterproof and
insulated (according to the provisions of the applicable standard);
- be made from materials ensuring lasting resistance to normal mechanical
stress, heat and the action of fumes or condensation;
- run vertically and be free of any constriction for its entire length;
- adequately insulated to avoid condensation or cooling of flue gas, in par-
ticular if installed outside the building or in rooms without heating;
- be adequately isolated from areas containing combustible and/or easily
flammable materials, either by air gap or suitable insulating sleeve;
- have a unit to collect any solid materials and condensate below the
aperture of the first flue at a height of at least 500mm, access to the unit
must be by way of an aperture fitted with a airtight metal door;
- have a round, square or rectangular inside section (in the latter two cases
with rounded angles of radius not less than 20 mm), however, hydrauli-
cally equivalent sections are allowed;
- have a terminal that complies with the specifications given below;
- without mechanical suction devices installed at the top of the duct;
- in flues passing inside or up against inhabited buildings, there must be
no pressure surges.
Appliances with natural draught can have single flues or multiple flues.
Single flues. The inside dimensions of certain types of single flues are
given in the specifications of the standard. If the actual system data does
not come within the application conditions or the limits prescribed in the
tables, calculate the flue according to standards.
Shared branched flues. In multi-storey buildings, shared branched flue
systems can be used for the removal of combustion products by natural
draught. Newly constructed shared branched flues must be designed us-
ing the following calculation method and meet the requirements of the
standard.
Terminals. Terminals are the devices installed on top of single or shared
branched flues. These devices are installed to facilitate dispersion of com-
bustion products also in adverse weather conditions and to prevent entry
of foreign matter.
Terminals must:
- have a cross-sectional area not less than the double of the flue/
chimney;
- be suitably designed to prevent rain or snow entering the flue/
chimney;
- be designed to ensure constant discharge of combustion products with
any direction or angle of wind.
The outlet height, corresponding to the top of the flue/chimney, regardless
of eventual terminals, must be outside the "downdraught zone", to avoid
the risk of back pressure preventing the free discharge of fumes into the
atmosphere. Therefore always observe the minimum heights indicated in
the figures in the standard, according to the pitch of the roof.
Direct discharge to the outside. Natural draught appliances, required to be
connected to a chimney or flue, can discharge fumes directly to the outside
by means of a duct passing through the external wall of the building. In this
case, the appliance is vented through a flue duct with a external terminal.
Exhaust duct. The exhaust duct must meet the same technical requirements
given for flues, with further provisions as per the current standard.
Positioning the draft terminals. Draft terminals must:
- be installed on external perimeter walls of the building;
- be positioned according to the minimum distances specified in current
technical standards.
Discharge of combustion products of natural draught appliances within
enclosed areas without roofs (ventilation pits, inner courtyards, etc.), direct
discharge of fumes is allowed for natural or forced draught gas appliances
with a heat output from 4 to 35 kW, provided the specifications of current
technical standards are complied with.
Important: never deliberately disable the fumes discharge control device.
Any part of said device, if damaged, must be replaced with original parts.
In case of recurrent intervention of the fumes exhaust control device, check
the flue and ventilation in the room where the boiler is installed.
1.7 Filling the system.
Once the boiler is connected, proceed with filling the system through the
filler cock (see figure page 91). The system should be filled slowly to ensure
that any air bubbles in the water can be released via the boiler and heating
system vents. The boiler is equipped with an automatic venting valve located
on the circulation pump. Open the vent valves on the radiators to allow air
to escape. Close the vent valves when water appears.
Close the filling valve when the boiler pressure gauge indicates approx.
1.2 bar.
N.B.: During these operations, start the circulation pump at intervals by
means of the main switch on the control panel. Vent the circulation pump
by unscrewing the front cap while keeping the motor running.
Screw on the cap on completion of the operation.
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