A
A
1.0m
1.0m YX
where:
X = 1.0m & Y = 0.5m or
X = 0.5m & Y = 1.0m
Fig 1 Minimum clearance distances
10
4. Installation of Air Heater(s)
4.1 General
Before installation, check that the local distribution conditions,
fuel specification, and adjustment of the appliance (see data
plate) are compatible.
Important:
Copper Sulphide / Black Dust
In some areas of the UK, particularly Northern Ireland, problems
have been experienced with copper sulphide (more commonly
referred to as Black Dust) forming on the inner surfaces of
copper gas supply pipework. This dust can enter the gas stream
and may lead to blockages of valves, filters and injectors.
If this heater is being installed in an area where Black Dust
is known to be a problem, and copper gas supply pipework is
used, it is recommended that a filter having a stainless steel 50
micron mesh and suitable for Natural Gas is fitted at the inlet
to the appliance immediately downstream of the main appliance
isolation valve. The end user should be advised that the filter
will require periodic cleaning or replacement at least once per
year, during the annual service, or more often if the problem is
severe.
4.2 Location
The location chosen for the air heater must permit:
- the provision of a satisfactory flue system and an adequate
air supply.
- adequate space for servicing and air circulation around the
air heater.
The heater(s) must not be installed in conditions for which it
is not specifically designed e.g. where the atmosphere is corrosive
or salty, and they are not suitable for outdoor use unless the
CP/EA style is specified. CP/EA heaters must be installed on
a plinth such that there is a minimum distance of 0.5m between
ground level and the lowest point of any air inlet grilles.
Where the location of the air heater is such that it might suffer
external mechanical damage e.g. from overhead cranes, fork
lift trucks, it must be suitably protected.
CP heaters are for normal operation within an ambient
temperature range of -10 to 25°C.
The air heater must be installed in accordance with the rules in
force and the relevant requirements of any fire regulations or
insurance company's requirements appertaining to the area in
which the heater is located, particularly where special risks are
involved such as areas where petrol vehicles are housed, where
cellulose spraying is carried out, in wood working departments
etc.
IMPORTANT:
Heaters shall not be installed in:-
a) Those parts of spaces within buildings that have been
classified as hazardous areas as defined in
BS 5345 : Part 2.
b) Where there is a foreseeable risk of flammable particles
or gases or corrosion inducing gases or vapours being
drawn into either the heated air stream or the air for
combustion. In such cases installation may only proceed
if the air to be heated is ducted to the heater from an
uncontaminated source, preferably from outside the
building. The option of taking combustion air from the
space is not permitted. In certain situations where only
airborne particles are present it may suffice to fit filters
on the main air inlet duct of the heater. Advice in these
instances may be obtained from Powrmatic Ltd.
c) In areas subjected to significant negative pressures due to
extract systems.
4.3 Installing the Air Heater
If necessary consideration should be given to mounting the
heater on resilient pads, or equivalent, to minimise transfer of
noise and vibration to the structure of the building.
Floor mounted heaters must be installed on a level
noncombustible surface.
Heaters mounted at high level must be supported on a purpose
designed platform or framework that is suspended from vertical
drop rods, chains or straps or mounted on specifically designed
cantilever brackets from a non-combustible wall. The method
of installation support must be capable of adequately supporting
the weight of the unit (See Table 2, Page ?) and any ancillary
equipment. Before installing the heater the existing structure
must be inspected to ensure it is suitable. All supports should
be protected against the effects of rust or corrosion.
Whichever method of mounting the air heater is used the
following minimum clearances for installation and servicing
must be observed.
To the front The depth of the heater
To the rear 1.0m
To at least one side 1.0m
On the opposite side 0.5m
Above the heater 1.0m
Any combustible material adjacent to the air heater and the flue
system must be so placed or shielded as to ensure that its
temperature does not exceed 65 °C.
If the method of mounting allows for any movement of the
heater it is essential that all gas, duct, and electrical connections
to the heater are made with flexible connections to maintain
continuity of connection.
4.4 Combustion Air Supply
In buildings having a design air change rate of less than 0.5/h,
and where heaters are to be installed in heated spaces having
a volume less than 4.7 m³/kW of total rated heat input grilles
shall be provided at low level as follows:-
(1) for heaters of heat input less than 60 kW, the total minimum
free area shall not be less than 4.5 cm² per kilowatt of
rated heat input.
(2) for heaters of heat input 60 kW or more, the total minimum
free area shall not be less than 270cm² plus 2.25 cm² per
kilowatt in excess of 60 kW rated heat input.
Where the air heater(s) are to be installed in a plant room the
plant room must have permanent air vents communicating
directly with the outside air, at high level and at low level.
Where only high level air vents are available, ducting down to
floor level for the lower vents should be used.
All air vents should have negligible resistance and must not be
sited in any position where they are likely to be easily blocked
or flooded or in any position adjacent to an extraction system
which is carrying flammable vapour.
Grilles or louvres should be so designed that high velocity air
streams do not occur within the plant room.
The basic minimum effective area requirements of the air vents
are as follows:
(a) Low Level (inlet)
(1) for heaters of total rated heat input less than 60kW:
9cm² per kilowatt of rated heat input.
(2) for heaters of total rated heat input 60kW or more:
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