5.3.7 Horizontal flue/chimney systems
1
315mm to 500mm
2
Flue trims
3
This bend is equivalent to 1 metre
Total equivalent length = A+B+C+2x90° bends
Important
Horizontal flue extensions should always be installed with a fall of
at least 1.5° from the terminal to allow condensate to run back to
the boiler.
The standard telescopic flue is suitable only for horizontal termination
applications. It allows for lengths between 315mm and 500mm from elbow
to terminal without the need for cutting. Extensions of 250mm, 500mm and
1m are available.
All fittings should be fully engaged. The approximate engagement is
40mm. Apply the lubricant supplied to the seal on each fitting to aid
assembly.
Tab.19 Maximum permissible equivalent flue lengths are:-
Horizontal concentric 60/100 Diameter 80/125 Diameter
10 metres 20 metres
Any additional "in line" bends in the flue system must be taken into
consideration.
Tab.20 Their equivalent lengths are:-
Concentric pipes 135° bend 0.5 metres
93° bend 1.0 metres
The elbow supplied with the standard horizontal telescopic flue kit is not
included in any equivalent length calculations.
Important
Flue length is measured from point (i) to (ii) as shown.
See
Read this section in conjunction with the Flue Installation Guide
supplied with the boiler. This document includes details of vertical
flue/chimney systems and plume displacement kits.
Warning
SUPPORT
- All flue systems MUST be securely supported at a
MINIMUM of once every metre & every change of direction. It is
recommended that every straight piece is supported irrespective
of length. Additional supports are available as accessories.
VOIDS
- Consideration must be given to flue systems in voids and
the provision of adequate access for subsequent periodic visual
inspection.
5.3.8 Flue/chimney trim
The flexible flue trims supplied can be fitted on the outer and inner faces of
the wall of installation.
Fig.19 Horizontal flues
Fig.20 Flexible flue trims
5 Before installation
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