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7.3 Flue System Specification
The Grant ‘Biomass’ 125mm (5in) flue
system is a fully insulated stainless
steel twin-wall flue finished with a Black
Polyester Powder paint finish.
This insulated flue system reduces the
possibility of the condensate freezing in
the flue, and also has a high corrosion
resistance suitable for solid fuel.
The CE designation of this ‘Biomass’
flue system (to BS EN 1856-1) is:
T450 N1 W V2 L50 G 60
Where:
T450 – Temperature rating – 450°C
maximum temperature for continuous
operation
N1 – Pressure rating – negative
pressure
W – Condensate resistance – able to
contain condensate within the flue
V2 – Corrosion resistance – resistant
to attack from products of combustion
from natural wood
L50 – Liner material – 316L stainless
steel
05 – Material thickness – 0.5mm
G – Soot fire resistance – tested at
1000°C for 30mins
60 – Distance to combustibles – 60mm
minimum clearance is required from
combustibles.
Masonry chimneys MUST be lined
using the 125mm stainless steel flexible
‘smoothbore’ liner – available as part of
the Grant ‘Biomass’ flue system. Refer
to Section 7.4.9 for further information
and the flue designation.
7.4 Flue System Assembly
7.4.1 Fan Box and Inspection Pipe
The fan box supplied with the boiler
(packed in the accessories box)
incorporates:
•
Exhaust fan
•
Draught stabiliser
•
Flue connection (to fit Grant
‘Biomass’ flue system)
The fan box is supplied with a neoprene
gasket for connection to the boiler. This
neoprene gasket is to accommodate
the low temperature wet flue system of
the Grant Spira boilers. Refer to Section
4.10 for fitting details.
The lead for the flue fan (supplied
factory-fitted to the fan box) is
connected to the same 5-way plug
as the lead for the wash system
solenoid valve. Refer to Section 8.3 for
connection details.
The flue system must include the Grant
Inspection Pipe (product code: WPB/IP)
supplied with the boiler. This should be
fitted to the outlet of the fan box. Refer
to Section 7.4.2 for guidance on how to
join flue components. The Inspection
Pipe incorporates a flue inspection
hatch and combustion test point. The
Inspection Pipe should be positioned
such that the cover plate faces to the
same side as the pellet hopper - but not
to the front or rear.
When fitting the Inspection Pipe to the
fan box, check the lip seal is fitted to
the inner flue liner of the flue connector
and the locking band is fitted to secure
the joint.
When installed, the draught stabiliser
must not be boxed in or obstructed
from operation in any way.
A condensate drain at the base of the
flue is not required as the ‘Biomass’
flue system is designed to allow the
condensate to run back into the boiler.
7.4.2 Joining Components
All the ‘Biomass’ system twin-wall flue
components (with the exception of
the elbows) use a ‘twist lock’ jointing
system. The ‘male collar’ end of the flue
component MUST always be uppermost
when fitted.
To join two components together:
All flue joints must have a lip seal
gasket fitted. This seal is supplied with
the flue component.
First fit the lip seal supplied into the
groove (in the inner flue liner) at the
‘male collar’ end of the flue component.
Refer to Figure 7-2. The lip seal should
be fitted ‘dry’, i.e. with no lubricating
grease applied at this stage. The
lubricating grease (also supplied with
the component) should be applied to
the seal after it is fitted but before fitting
the two flue components together.
Loosen the locking band at the ‘female
collar’ end. Insert the ‘male collar’ into
the ‘female collar’ and twist through 1/6
of a turn to lock in place. Refer to Figure
7-3.
Ensure that the two beaded ends of
the flue components are in contact
with each other all round. Position the
locking and so that it grips the beaded
edge of both components and fasten
using the spring clip. The locking bands
provided MUST be fitted at ALL flue
joints. Refer to Figure 7-4.
To allow for alignment, the female
collars of the elbows do NOT have the
twist lock flutes, but the locking band
MUST still be used to secure the two
flue components together.
Figure 7-3:
Twist lock joint between
components
Figure 7-2:
Male and female flue
connections
Male collar
Insulation
Female collar
Viton gasket
seal detail
!
NOTE
The combustion test point in the
flue inspection pipe must NOT be
used to monitor and adjust the %
CO2 when commissioning the Spira
boiler. The combustion test point,
located at the left rear corner of the
rear access cover (on the secondary
heat exchanger) must only be used
for this purpose. Refer to Section
10.10 of these instructions for
further details.
