Technical data

capable of adequately supporting the weight
of the unit and ancillary equipment .
2.3 Warm Air Circulation
The air heater should be positioned to enable
maximum circulation of discharged warm air
within the area to be heated, whilst taking
account of personnel within the area,
sources of cold air ingress , and obstructions.
Ensure louvres are adjusted outwards
and ensure blades are not resonating
The air temperature rise on passing the heat
exchanger is typically around 34
0
C
A full and unobstructed return air path to the
air heater must be provided
(see 2.4 Air Supply).
Where the heater is positioned to deliver
blown air through an opening in a wall, return
air intakes should be located so that they
cannot become blocked. Similarly these
intakes must be positioned so as not to draw
in odours, fumes, hazardous vapours or
particles.
2.4 Air Supply for Combustion and
Ventilation
Consideration must be given to the provision
of air for the purposes of combustion and
ventilation of the heated space, plant room or
enclosure where the heaters are to be
installed .
It is strongly recommended that BS 6230 :
2005 is referred to for further information
concerning ventilation requirements
2.4.1 Heaters installed within the
heated space
Where heaters are installed within the heated
space (i.e. not a plant room , or enclosure )
then
Combustion air or heater related ventilation
air will not be required if -
 The heaters are installed in room
sealed mode (ie with a positive
connection to atmosphere of both flue
and combustion air)
OR
 If the design air change rate of the
heated space is 0.5 air changes per
hour or greater
The design air change rate may be satisfied
by natural infiltration or by mechanical
ventilation.
Combustion air ventilation
will be required if
 The heater(s) are installed with flue
only (ie without the positive connection
to atmosphere of a combustion airduct)
And
 The design air change rate of the
heated space is less than 0.5 air
changes per hour
Where heater(s) are installed without the
positive connection of combustion ductwork
within a heated space where air change rate
of that heated space is less than 0.5 air
changes per hour then it will be necessary to
provide either natural ventilation openings to
the heated space (Section 2.4.1.1 refers)
or the mechanical ventilation of the heated
space (Section 2.4.1.2 refers)
2.4.1.1
Natural Ventilation Openings to the
Heated Space
If the heater(s) are to be installed without the
positive connection of combustion air
ductwork within a heated space, and where
the design air change rate of that heated
space is less than 0.5 air changes per hour,
then provision for low level natural ventilation
openings only will be necessary.
The minimum free area of the low level
natural ventilation opening shall be
 2 cm
2
for each kW of rated heat input
The low level natural ventilation opening
should be situated on an external wall and be
within 1000 mm of floor level for natural gas
and ideally at floor level for lpg gas
installations but in any event no higher than
250 mm.
The table below provides specific data for