Flue Equivalent Length Calculation - andrews NEOflo SC25/200 Installation, Operation And Maintenance Manual

FLUE SYSTEMS
Th e appliance can be installed using a number of alterna-
tive arrangements depending upon the installation re-
quirements It is delivered with its two 80 mm connection
points combined into a 80/125 concentric outlet on the
left. Flue components are ordered separately as required.
Available Flue Types
Open Flue (Type B )
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Th is is an open fl ued arrangement where the air for com-
bustion is drawn from the Water Heater room and because
of this the room must be ventilated. If the Heater is
installed in a compartment then it will require both a high
level and a low level vent. See Page 17.
Th e fl ue products are discharged either horizontally or
vertically using any of the supplied separate duct compo-
nents.
Room Sealed (Type C
xy
Th ere are a two approved room sealed arrangements
where both the air inlet and fl ue discharge terminate
outside the building.
Type C Flue and air ducts terminate horizontally in the
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same position
Type C Flue and air ducts terminate vertically in the
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same position
Flue and air ducts are supplied to a concentric design
(80/125). See Fig. 6.1 for component choices.
Flues should slope back to the Heater by 3 degrees.
Terminal positions must comply with the requirements
detailed in Fig. 6.6.

FLUE EQUIVALENT LENGTH CALCULATION

Th e combustion fan fi tted to the appliance moves the air
and fl ue products through the system and can provide
suffi cient capacity for a Flue Equivalent Length (FEL) of
20 metres for type C and C
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type B system.
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Each fl ue accessory such as bends and straight lengths
restrict the fl ue system and have a FEL which must be
added together to determine the total.
NB: For C and C systems the Terminal and the Twin
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Flue to Concentric Adapter do not have to be included,
they have already been taken into account.
Referring to the diagrams Fig. 6.2, 6.3, 6.4, 6.5 select a
suitable fl ue system for the particular installation require-
ment and then calculate the FEL of the system, this must
not be greater than that stated above.
NEOfl o Water Heater
)
systems and 40 metres for
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Examples:
A C Concentric fl ue system that uses one straight length
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and one 90° bend.
1 x 1m straight length
1 x 90° bend
Total (within 20m limit)
A C or C Concentric system that rises from the Heater and
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uses eight straight lengths and seven 90° bends.
8 x 1m straight lengths
7 x 90° bends
Concentric Adapter
Terminal
Total (within 20m limit)
Open Flue Type B
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Th e maximum FEL of fl ue in this confi guration is 40 metres.
Th e air inlet connection to the appliance must be fi tted with
a Debris Guard. Air is drawn from the room or compartment
in which the heater is installed and therefore the room or
compartment must be ventilated. See Page 17.
Th e fl ue duct can discharge either vertically or horizontally
by selection of the correct fl ue terminal. Th e fl ue pipe can
be fi tted with 90 and 45 degree bends as well as exten-
sions.
Example:
A B system with air collected from the plant room and the
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fl ue exiting via four straight length and four 90° bends to a
roof terminal.
4 x 1 m straight lengths of FLUE.
4 x 90° bends of FLUE
1 x Roof Terminal
Total (within 40m limit)
Flue support
All installed fl ues, vertical or horizontal, should be sup-
ported every 1m using the appropriate brackets.
Fixing the Wall Terminal
A hole size of 175mm is recommended. Th e terminal should
be installed with a three degree slope back to the Heater
and the gap around it fi lled with mortar, both on the inside
and outside. (See Fig 6.5). Wall plates can then fi xed inside
and out to present a clean fi nish.
Fixing a Vertical Terminal
A suitable fl ashing for the roof angle should be selected and
fi tted to the vertical terminal. Th e Terminal should then be
fi tted to the roof, securing it from below with the appropri-
ate bracket. (See Fig 6.5)
12
1.0
1.5
2.5
8.0
10.5
0.0
0.0
18.5
4.0
14.0
6.6
24.6
September 2015