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© Baxi Heating UK Ltd 2012
General Requirements for Horizontal Flue
Terminations
Detailed recommendations for flueing are given in
BS5440: Part 1. The following notes give general
guidance. The horizontal balanced flue terminal must
be installed so that it is exposed to external air,
preferably on a clear expanse of wall. Acceptable
positions are indicated in Fig. 5. Avoid positions where
the terminal is adjacent to projections; particularly
immediately under a balcony, inside a re-entrant
position, or immediately adjacent to a drain pipe. If the
boiler is fitted under a ventilator or opening window, the
terminal must be at least 300 mm from any part of the
window or ventilator and in accordance with BS5440:
Part 1.
The flue pipe must not be closer than 25 mm to
combustible material. Additional clearance must be
provided when passing the flue through timber walls.
Advice on gas installations in timber framed buildings is
contained in IGE technical publication IGE/UP/7
available from the Institution of Gas Engineers, 21
Portland Place, London W1N 3AF.
Guidance notes for Flue Installation
Read these Installation Instructions before installing
the boiler
. Before starting an installation, check that the
correct flue kit has been supplied with the boiler.
Detailed recommendations for flue installations are given
in BS 5440:1: 2000. The following notes are for general
guidance only.
a) The flue system must be constructed using only
Promax approved components.
b) It is important that the position of the terminal allows
free passage of air across it at all times.
c) It is ESSENTIAL TO ENSURE that products of
combustion discharging from the terminal cannot re-
enter the building, or any other adjacent building,
through ventilators, windows, doors, other sources of
natural air infiltration, or forced ventilation / air
conditioning.
d) The minimum permissible dimensions between the
flue terminal and obstructions and ventilation
openings are specified in the table on page 13 of
these instructions.
e) If the flue terminal discharges into a pathway or
passageway check that combustion products will not
cause nuisance and that the terminal will not obstruct
the passageway.
f) Where terminals are fitted within 850 mm of a plastic
or painted gutter, or 450 mm of painted eaves, an
aluminium shield at least 750 mm long must be fitted
to the underside of the plastic or painted surface.
g) Where installation will be in an unusual location,
special procedures may be necessary. BS 6798 gives
detailed guidance on this aspect.
h) As the Promax Store is a condensing boiler the flue
duct must have a fall back to the boiler of at least
1.5°.
j) The efficient condensing operation of the Promax
HE Store will naturally give rise to condensation in the
flue gases and
pluming will occur in all but the
most favourable atmospheric conditions
. Some
condensate may also be discharged from the
terminal. The terminal must, therefore, be
sited to
avoid nuisance from either phenomenon
.
k) Where the lowest part of the terminal is less than 2 m
above the level of any ground, balcony, flat roof or
place to which people have access, the terminal must
be protected by a guard of durable material.
