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9
Flue System and Air Supply
9.1 Low Level discharge Flue
The Grant VORTEX Pro External combi
is supplied with a low level discharge
flue (see Section 4).
The minimum dimensions for locating
the standard terminal from building
features (windows, doors, etc.) are
shown in Figure 9-1.
The terminal must be positioned so
as to avoid products of combustion
accumulating in stagnant pockets
around the buildings or entering into
buildings. Care should be taken that the
plume from condensed flue gases does
not cause a nuisance.
Where it is not practical to use this flue,
the External module may be fitted with
an alternative flue system available from
Grant UK.
Under no circumstances can the
External module be installed with an
existing flue system. Only Grant flue
systems and components suitable
for wet flues should be used.
Failure to install the correct type
of flue system will invalidate the
guarantee.
!
nOtE
Figure 9-1:
Clearances for low level discharge flues
Key
Location of outlet
Pressure jet
Condensing
A
Directly below an opening, air brick opening, opening window, etc.
600
1000 **
B
Horizontally to an opening, air brick opening, opening window, etc.
600
1000 **
C
Below a gutter, eaves or balcony with protection
75 *
1000 **
D
Below a gutter, eaves or balcony without protection
600
1000 **
E
From vertical sanitary pipework
300
F
From an internal or external corner
300
G
Above ground or balcony level
300
H
From a surface or boundary facing the terminal
600
2500 **
J
From a terminal facing the terminal
1200
K
Vertically from a terminal on the same wall
1500
L
Horizontally from a terminal on the same wall
750
M
Above the highest point of an intersection with the roof
600
N
From a vertical structure to the side of the terminal
750
O
Above a vertical structure less than 750 mm from the side of the termin-
al
600
P
From a ridge terminal to a vertical structure on the roof
1500
Q
Above or to the side of any opening on a flat or sloping roof
300
R
Below any opening on a sloping roof
1000
S
From oil storage tank (Class 1)
1800 ***
*
A heat shield at least 750 mm wide must be fitted to provide protection of combustible material.
**
Clearances required by BS 5410-1:2014 to alleviate the effect of plume nuisance. If a risk assessment shows that there will be no
impact from pluming, then the ‘pressure jet’ figure could apply - seek confirmation from Local Authority Building Control.
***
Seek guidance from OFTEC Book 3 (Oil Storage and Supply).
Clearances advised by Grant Engineering (UK) Limited in accordance with British Standards.
Minimum distances to terminals in millimetres as measured from top of the chimney or the outer edge of a low level discharge opening.
Terminals should be positioned so as to avoid products of combustion accumulating in stagnant pockets around the building or entering into buildings and with a balanced flue,
the free intake of air.
Care should also be taken to ensure that the noise and plume from a condensing flue does not cause a nuisance.
