andrews 10/105, Installation And Service Manual

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3 Installation
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Guidance for flue installation are given in BS 6644, BS5440
Pt 1 and British Gas publication IM/11 - Flues for Commercial
and Industrial Gas Fired Boilers and Air Heaters.
The flue connection is designed for BS 835 type heavy duty
flue, but light quality flue pipe, mild steel or stainless steel
sheet may be used using the appropriate adapter. Flue pipes
etc. shall be fitted socket-up to keep any condensate within
flue and appliance. Flues up to 200mm diameter should be
fitted with a suitable British Gas Certified terminal.
Fig 2.
The terminal position is most important and must be at least
1000mm above roof surfaces or at least 600mm above any
parapet and clear of any adjacent obstruction as well as
being clear of any openable windows, ventilators or features
which could allow re-entry of flue products into the building.
Pressure areas should also be avoided to prevent
blowdown.
See recommendations in BS 6644. BS 5440 Part 1
also provides useful additional advice.
Flue materials, including jointing materials and fittings shall
be asbestos-free, robust, durable, corrosion resistant and
non- combustible and shall comply with BS 5854 and BS 715
or BS 4076 as appropriate, as well as being of a type
accepted by the Local Gas Authority.
When passing up through or adjacent to combustible
materials, measures shall be taken to prevent the temperature
of the combustible material from exceeding 60°C. The flue
shall not be closer than 50mm to any combustible material
except when passing through, when it must be enclosed by a
non- combustible sleeve and separated from the sleeve by not
less than 25mm air space.
Flues shall be of a size not less than specified in Section 2,
Technical Data (i.e. nominal flue size) and fitted so that there
is no risk to persons in the building or from accidental damage
Fig 3.
If using an existing brick chimney, it should be swept and
lined and checked for soundness before connecting the flue
and should take the shortest possible route and rise
continuously to the terminal avoiding the use of 90° bends
where a change of direction is required. Horizontal and very
shallow runs of flue should be avoided since they impede the
flow of gases and increase local cooling.
*A minimum of 600mm of vertical flue directly above the
draught diverter should be provided where possible on all
natural draught flue installations. If this dimension cannot be
achieved please contact Andrews Water Heaters.
Note
Please note this is not required where a common flue
header is used on multiple installations.
Terminal
1000mm
Minimum
Roof
1 2 3
Split flue clip
600mm*
1. This flue run
must not be used
2 & 3 are recommended flue runs
Fig.2
Fig.3
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