Flue System and
Air Supply
31
Under no circumstances can Grant
Vortex boilers be installed with
e
xisting flue systems. Only flue
systems and components suitable for
wet flues should be used.
Failure to install the correct type of
flue system will invalidate the
warranty.
Grant condensing boilers have high
operating efficiencies and low flue gas
temperatures. Care must be taken to
ensure the flue system is suitable for the
very low flue gas temperatures and
condensate in the flue gases.
Suitable conventional flue systems are
available from Grant UK.
The flue must terminate in a down
draught free area, i.e. at least 600mm
above the point of exit through the roof
or preferably above the ridge level.
The condensate may be allowed to run
back into the boiler. A condensate drain
at the base of the flue system is not
required.
The high level flue terminal must be at
least 600mm from any opening into the
building, and 600mm above any vertical
structure or wall less than a horizontal
distance of 750mm from the terminal.
If an existing chimney is to be used, it
must be lined with a smooth bore
stainless steel liner suitable for use with
oil fired condensing boilers. The top and
bottom of the annular space must be
sealed.
Grant recommends the use of the Grant
'Orange' flue system, specifically
designed for the Vortex range of
condensing boilers.
The internal flue liner diameter for all
models is 100mm (4 in).
9.2 Conventional Flue Systems
The maximum vertical height (from the
top of the boiler to the terminal) for the
'Orange' system is 19 metres.
If a rigid flue is used externally,
i
t must be of the twin-wall type
incorporating seals at all joints,
constructed with a stainless steel inner
skin and be suitably insulated and
weatherproofed. The internal flue
d
iameter for a rigid flue for all models
is 100mm (4 inches).
Grant recommends the use of a hybrid
system using Grant 'Green' and
‘Orange’ flue system components for
this application. Refer to Section 1.2
for details.
As no flue adaptor is supplied with
the boiler, in order to correctly
connect the hybrid system, it will be
necessary to purchase the Grant CF
adaptor kit (Ref. CFA15/70).
If required, it is possible to use the white
painted single-wall straight flue
extensions, adjustable extensions and
elbows from the Grant 'Orange' system
for the internal section of the flue
system, see Fig 9-5. These components
can be fitted between the boiler
connector and flue adaptor. The flue
adaptor, to which the external twin-wall
'Green' flue components are connected,
can therefore be situated just before the
flue system passes through the wall.
Grant 'Orange' system single-wall
f
lue components must not be used
externally.
The maximum vertical height (from the
top of the boiler to the terminal) for the
100mm diameter hybrid 'Green/Yellow'
system is 8 metres.
Grant ‘Green’ twin-wall flue is
recommended for externally run flues
t
o reduce the possibility of the
condensate freezing in the flue.
No part of any flue system should be
made of an asbestos material;
aluminium must not be used in any part
of the flue. Only stainless steel flue
components should be used.
If the draught conditions are
satisfactory, the flue should terminate
with a standard cowl.
Refer to the locally applicable Building
Regulations, BS 5410:1 and OFTEC
Installation Requirements (OFTEC
Books 2 and 3) for further guidance on
conventional flue systems.
It is important to ensure that the flue
system is sealed and that condensate
cannot escape. Up to 1.5 l/h of
condensate can be produced in a
conventional flue system.
Use only flue systems suitable for oil
fired condensing boilers.
Do not use fire cement. The use of high
temperature silicone sealants is
recommended.
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NOTE
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NOTE
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NOTE
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CAUTION
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