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WD420/3/2007
Alternatively, where flue or air intake lengths of up to 60m are require, Keston Composite
75mm flue and air pipe can be used (contact your KESTON Heating stockist for details).
Keston Composite 75mm pipe MUST be painted where exposed to UV light.
Both 50mm flue outlet terminal and 50mm air inlet terminal are supplied and are illustrated
in Figure 3.8.1. Both terminals are identical. If 75mm terminals are required these can be
obtained from your KESTON Heating stockist. Request part numbers C.17.2.26.00.0
(terminals) and C.17.2.00.60.0 (50 to 75 adapters).
3.8.2
Maximum Lengths
The maximum lengths of both air inlet pipe and flue outlet pipe, when no bends are used,
are as detailed below.
However, each bend used has an equivalent length that must be deducted from the
maximum straight length stated above. Knuckle bends must not be used.
o
A 92.5
sweep elbow is equivalent to 1.0m straight length. A 45
0.5m straight length.
Maximum Air Inlet Length
Maximum Flue Outlet Length:
Maximum Total Flue and Air Intake Length :
Example (assuming 50mm muPVC flue and air pipework)
Air inlet uses two 92.5
Hence, maximum length permissible
(i.e. a+b in figure 3.8.2) = 39.0m - 1.0m -
1.0m = 37.0m
Flue outlet uses one 92.5
Hence, maximum length permissible (i.e.
c+d in figure 3.8.2 = 20.0m - 1.0 m = 19.0m
3.8.3
Slope
'Horizontal' flue outlet pipework MUST slope
at least 2 degrees (35 mm per metre run)
downwards towards the boiler. Pipework
can be vertical. Only swept elbows can be
used.
Air inlet pipework can be truly horizontal or
vertical, or sloping in a downward direction
towards the boiler but in this case rain, etc.,
must be prevented from entering the pipe.
There must be no troughs in any of the
pipework, whether it be air inlet or flue
outlet.
Due the low temperature of the flue gases
further condensate will form within the flue
system. Drain points, with suitable traps,
must therefore be incorporated within the flue
system at the base of vertical flue sections in
excess of 6m, for 50mm muPVC pipe flue
systems. These additional condensate drains
must be run to discharge as detailed in
Installation & Servicing Instructions
Chapter 3 : Boiler Location
o
sweep elbows.
o
sweep elbow.
The Keston Qudos 28s & Qudos 28sP Boilers
50mm
:
39.0m
20.0m
40.0m
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KESTON Qudos 28s
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7R %RLOHU
o
bend is equivalent to
75mm
117.0m
60m
120.0m
$,5
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7HH )LWWLQJ
LQ PLQ
Page : 18
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