3. General Requirements
3.1 Related Documents
The installation of the air heater(s) must be in accordance
with the rules in force and the relevant requirements of the
Gas Safety Regulations, Building Regulations and the
I.E.E. Regulations for Electrical Installations.
It should be in accordance also with any relevant
requirements of the local gas region, local authority and fire
authority and the relevant recommendations of the following
documents.
British Gas Plc Publications
IM/11 : 1989 Flues for Commercial and Industrial Gas Fired
Boilers and Air Heaters
IM/16 : 1988 Guidance notes for the installation of gas
pipework, boosters and compressors in Customer’s
premises (excluding domestic installation of 25mm and
below).
British Standards Code of Practice
BS 6230: 1991 Installation of Gas Fired Forced Convection
Air Heaters for Commercial and Industrial Space Heating.
3.2 Location
The location chosen for the air heater must permit the
provision of a satisfactory flue system and an adequate air
supply. The location must also provide 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 where high wind speeds may affect
burner operation, and they are not suitable for outdoor use.
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.
TE units are designed to operate in a maximum ambient
temperature of 25 °C.
3.3 Gas Supply
3.3.1 Service Pipes
The local gas undertaking should be consulted at the
installation planning stage in order to establish the availability
of an adequate supply of gas. An existing service pipe must
not be used without prior consultation with the local gas
undertaking.
3.3.2 Meters
A gas meter is connected to the service pipe by the local
gas undertaking or a local gas undertaking contractor. An
existing meter should be checked, preferably by the gas
undertaking, to ensure that the meter is adequate to deal
with the total rate of gas supply required.
3.3.3. Installation Pipes
Installation pipes should be fitted in accordance with
IM/16:1988. Pipework from the meter to the air heater must
be of adequate size. Do not use pipes of a smaller size than
the inlet gas connection of the heater. The complete
installation must be tested for soundness as described in
the above Code. The complete installation must be tested
for soundness as described in BS 6230.
3.3.4. Boosted Supplies
Where it is necessary to employ a gas pressure booster
the controls must include a low pressure cut off switch at
the booster inlet. The local gas undertaking must be
consulted before a gas pressure booster is fitted.
3.4 Flue System
Detailed recommendations for fluing are given in BS 5440,
Part 1 (Flues) and IM/11.
The air heater must be connected to a closed flue system.
The cross sectional area of the flue serving the appliance
must be not less than the area of the flue outlet to the air
heater.
Materials used for the flue system should be mechanically
robust, resistant to internal and external corrosion,
noncombustible and durable under the conditions to which
they are likely to be subjected.
Prevention of condensation within the flue should be an
important factor in the design of the flue system. In order to
minimise condensation the use of double walled flue pipe
or insulation is recommended. If double walled flue pipe is
used it should be of an acceptable type.
Where condensation in the flue is unavoidable provision
should be made for condensation to flow freely to a point at
which it can be released, preferably into a gully. The
condensation pipe from the flue to the disposal point should
be of non-corrodible material of not less than 22mm (1/2")
size.
Facilities should be made for disconnecting the flue pipe(s)
from the air heater(s) for inspection and servicing purposes.
The flue should terminate in a freely exposed position and
must be so situated as to prevent the products of combustion
entering any opening in a building in such concentration as
to be prejudicial to health or a nuisance.
An approved terminal must be fitted at the flue outlet.
3.5 Air Supply
In buildings having a design air change rate of less than
0.5 /h, and where TE heaters are to be installed in heated
spaces having a volume less than 4.7 m
3
/kW of total rated
heat input grilles shall be provide at low level as follows:-
The total minimum free area shall not be less than 270cm
2
plus 2.25 cm
2
per kilowatt in excess of 60 kW rated heat
input.
The air vent(s) should have negligible resistance and must
not be sited in any position where it is likely to be easily
blocked or flooded or in any position adjacent to an
extraction system which is carrying flammable vapour.
3.6 Air Distribution System
Care should be taken to avoid impeding the air throw with
racking, partitions, plant or machinery etc.
A full and unobstructed return air path to the air heater(s)
must be provided.
Care must be taken to ensure that return-air intakes are
kept clear of sources of smells and fumes, and in special
circumstances where there is any possibility of pollution of
the air by dust, shavings etc., precautions must be taken
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