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FLUE INSTALLATION
It is the responsibility of the installer to
IMPORTANT.
ensure, in practice, that products of combustion dis-
charging from the terminal cannot re-enter the building
or any other adjacent building through ventilators, win-
dows, doors, other sources of natural air infiltration, or
forced ventilation / air conditioning.
If this should occur the appliance MUST be isolated from
the gas supply and labelled as 'unsafe' until corrective
action can be taken.
Terminal Position
Due to the high efficiency of the boilers pluming will occur.
Particular care should be taken in the case of large output
boiler installations in complying with the requirements of the
Clean Air Act.
The flue must be installed in accordance with the appro-
priate Building Regulations and standards listed on
8
and in compliance with BS6644. In IE refer to
I.S.820:2000.
FLUE SYSTEM DESIGN
Due to the high efficiency of these boilers, the flue gas
temperatures are low and the buoyancy in the stack will be
relatively small. The boiler is supplied with an integral fan
which is fully matched to the boiler in each case to provide
correct combustion air flow and overcome the flue re-
sistance.
The power of this fan is such that there is a large reserve of
pressure available to overcome a significant length of flue
without affecting the combustion performance of the boiler.
The maximum pressure available at the base of the flue to
overcome flue resistance is
culations should include the resistance of any air ducts
used to connect the air inlet direct to outside air. Care
should be taken with tall flue systems to ensure excess
buoyancy is not created. A negative pressure must not be
created at the boiler flue outlet. All horizontal flue lengths
must have a fall back to the boiler of 3°
See table below for approximate maximum straight flue
length.
The addition of elbows and their positions in the flue will
have a significant effect on the maximum allowable flue and
air duct lengths. Consult with your flue supplier for detailed
design work
MODELS 300
FLUE OUTLET
DIAMETER (mm)
STACK PRESSURE
(at max. power)
MAX. EQUIV.
FLUE LENGTH (m)
page
shown in the table below.
Cal-
303
304
80
100
260
260
18
28
Boiler Type (PD CEN/TR 1749:2014)
C63 = A room sealed appliance intended to be
connected to a separately approved and
marketed system for the supply of combustion
air and discharge of combustion products.
The fan is up stream of the combustion
chamber.
B23 = An appliance intended to be connected
to a flue which evacuates the products
of combustion to the outside of the room
containing the boiler. The combustion air is
drawn directly from the room. The fan is up
stream of the combustion chamber.
IMPORTANT NOTE.
If combustion air is drawn from within the boiler room,
ensure no dust or airborne debris can be ingested into
the appliance. Dusty concrete flooring should be
sealed to reduce the presence of dust. Ideally where
possible duct the air supply into the boiler room from a
clean source outside the boiler room / building.
Where it is not possible to duct air from outside the
boiler, the air inlet guard MUST be used,
Material
With no requirement for buoyancy to discharge flue
products and with low flue gas temperatures, single wall
flues are suitable for most installations. Care should still
be taken to maintain compliance with building regulations
and relevant standards.
The flue used should be a suitably approved flue for use
on a pressurised condensing flue system. Materials
choice includes plastic, aluminium and 316 grade
stainless steel. Unless the flue is manufactured from
aluminium, the condensate from the flue must be
collected and drained before entering the sump of
the boiler (when employing the vertical combined
(cascade) flue outlet header, a flue condensate drain is
provided for this purpose).
Advice regarding the availability of proprietary types of
flue system can be obtained by contacting Ferroli Ltd. All
joints or connections in the flue system must be
Impervious to condensate leakage.
Low points in the flue system should be drained using
pipe of material resistant to condensate corrosion. All
drains in the flue should incorporate a water trap.
Care should also be taken in the selection of flue
terminals as these tend to accentuate the formation of a
plume and could freeze in cold weather conditions.
Care should be taken to ensure the specification of the
chimney is suitable for the application by reference to
the manufacturers literature.
305
306
110
125
180
210
20
30
307
160
190
40
10
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