1.3.1. Related Documents
Installation of air heaters must be in accordance with the
relevant requirements of:
BS 5410: Part 2: 1978 Code of Practice for Oil Firing
Installations of 45kW and Above
The Building Regulations
The I.E.E. Regulations
It should also be in accordance with relevant require-
ments of the local authority and fire authority, in addition
the following British Standard Codes of Practice must be
observed CP.3 Ch IV Precautions Against Fire Part 2
Shops and Departmental Stores Part 3 Office Buildings.
OFTEC Technical Book 3: Domestic & Commercial
requirements for oil storage and supply equipment.
OFTEC Technical Book 4: Oil fired appliances & system
installation requirements.
OFTEC Easy Guides to non domestic oil feed pipes and
oil storage.
1.3.2 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 facilitate ease of servicing
and satisfactory air circulation around the heater.
The air heater must be installed strictly in accordance with
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, cellulose spraying
areas, and wood working departments etc.
The air heater must be installed either:
(a) suspended by chains or straps of adequate strength to
safely carry the weight of the unit and ancillary equipment
or
(b) On specifically designed cantilever brackets from a
non-combustible wall or
(c) On a level non-combustible surface which is capable
of adequately supporting the weight of the air heater and
any ancillary equipment.
The heater must not be installed in conditions for which it
is not specifically designed e.g. highly corrosive atmo-
spheres, vitiated atmospheres, or where adverse wind
conditions may be experienced. Where the location of the
heater is such that it might suffer external mechanical
damage e.g. from overhead cranes, fork lift trucks etc. it
must be suitably protected. Any ducting should be kept as
short and direct as possible having regard to the distribu-
tion of the heated air.
OUH Range Users, Instrucons & Service Instrucons Issue 5.1 September 2015 Page 9
Any combustible material adjacent to the heater and flue
systems must be so placed as to ensure that its tempera-
ture does not exceed 65°C (150°F).
1.3.3 Main Storage Tank and fittings
Construction and installation should be in accordance
with:
(a) BS 5410 Part 2 Section 6
(b) BS 799 Part 5
(c) BS 1563
The latter three standards apply to cast iron sectional,
mild steel sectional, and mild steel welded tanks respec-
tively and therefore must be applied appropriately.
1.3.4 Service Tanks and fittings
1.3.4.1 Construction
These should be designed and constructed in accor-
dance with BS 799 Part 5
1.3.4.2. Installation
The installation should be in accordance with:- BS 5410
Part 2.
In addition the service tank installation must comply with
local regulations and by-laws and with the requirements
of insurance companies
1.3.5 One Pipe System (Storage to
burner)
1.3.5.1 General
Refer also to the detail provided in the burner handbook
regarding pipe sizing. These must be generally in accor-
dance with B S 799 Part 3 and BS 5410 Part 2.
Particular attention is drawn to the following:
a) Pipe jointing compounds must be capable of withstand-
ing the solvent action of the fuel oil under all operating
temperatures and pressures. Jointing compounds
containing oil shall not be used. Hemp and other fibrous
materials shall not be used as packing for screwed joints.
b) Soft solder copper tube fittings and galvanised pipes
and fittings must not be used.
c) Oil lines must be completely air-tight.
d) The pump suction must not exceed a maximum of 0.4
bar (30cm Hg). Beyond this limit gas may be released
from the oil.
1.3.5.2 Single Pipe System - Gravity
Feed
Warning: The burners are supplied adjusted for a single
pipe system. If the burner is to be used on a twin pipe
system the Internal bypass plug of the burner oil pump
must be fitted. Refer to the burner instruction booklet.
Ideally the return pipe should terminate within the oil tank
at the same level as the suction line, both being below the
minimum oil level.
1.3.6 Fire Valve
It is recommended that the fire valves should be installed
as follows:
1. Main storage to service tank supply (if applicable)
2. Main storage to burner supply
3. Service tank to burner supply (if applicable)
Fire valves should be installed generally in accordance
with the requirements of BS 799: Part 5. The fire valve
should be situated in an easily accessible position as near
the tank as possible and where practicable within the
boundary of the tank chamber or catchpit retaining wall.
1.3.7 Flue System
The flue system should generally be in accordance with
BS 5410 Part 2.
Materials used for the flue system should be mechanically
robust, resistant to internal and external corrosion,
non-combustible 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 insula-
tion is recommended.
Where condensation in the flue is unavoidable, or rain
ingress is possible, provision must be made for a conden-
sate drain connected to a suitable drain or gully. The
condensation pipe from the flue to the disposal point
should be of non-corrodible material of not less than
22mm (¾ in) size.
Facilities should be provided for disconnecting the flue
pipe from the air heater for inspection and servicing
purposes. Bends with removable covers should be fitted
for inspection and cleaning purposes where considered
appropriate.
The flue should terminate in a freely exposed position and
must be situated such that products of combustion do not
enter any opening in a building in such concentration as
to constitute a health hazard.
1.3.8 Combustion & Ventilation Air
Supply
Where the air heater is to be installed in the space to be
heated it requires the space containing it to have a perma-
nent air vent direct to outside air. The air vent should have
negligible resistance and must not be sited in any position
where it is likely to be easily blocked or flooded, neither
should it be positioned adjacent to an extraction system
carrying flammable vapour.
The air supply requirement that follows is related to the
maximum rated heat input of the heater, or heaters if more
than one is installed in the same space.
Total Input Rating Air Vent Area
of Air Heaters (Air direct-from outside)
Up to 60kW 4.5 cm²/kW in excess of 7kW
From 60kW up to 730kW 4.5 cm²/kW
Where the air heater is to be installed in a plant room, the
heater requires the plant room housing it to have perma-
nent air vents communicating directly with the outside air,
at high and low level. Where communication with the
outside air is possible only by means of high level air
vents, ducting down to floor level for the lower vents
should be used. Air vents should have negligible resis-
tance and must not be sited in any position where they are
likely to be easily blocked or flooded, neither should they
be positioned adjacent to any extraction system carrying
flammable vapour.
Grilles or louvers should be so designed that high velocity
air streams do not occur within the plant room.
The air supply requirements stated below are related to
the maximum rated heat input of the air heater(s). The
minimum free area requirements of the air vents is given
below.
Total Input Rating Position of Air Vent Areas
of Air Heater(s) Vents (Air direct from
outside)
Up to 730kW High Level 4.5cm²/kW
Low Level 9.0 cm²/kW
1.3.9 Air Distribution System
Where single OUH units are required to cover a large floor
area, and in buildings with high roof or ceiling heights
Calecon thermal economiser units should be fitted to
ensure even heat distribution and minimise stratification.
Care should be taken to avoid impeding the air throw with
racking, partitions, plant or machinery etc. Various outlet
configurations are available as optional extras to modify
the air throw pattern to suit particular site conditions.
For ducted units all delivery and return air ducts, including
air filters, jointing and any insulation or lining must be
constructed entirely of materials which will not contribute
to a fire, are of adequate strength and dimensionally
stable for the maximum internal and external tempera-
tures to which they are to be exposed during commission-
ing and normal operation.
Where inter-joist spaces are used as duct routes they
should be suitably lined with a fire-resisting material.
A full and unobstructed return air path to the air heater(s)
must be provided.
If the air heater(s) is installed in a plant room the return air
intake(s) and the warm air outlet(s) from the heater(s)
must be fully ducted, into and out of the plant room to
avoid interference with the operation of the heater.
The openings in the structure of the plant room through
which the ducting passes must be fire stopped.
Care must be taken to ensure that return-air intakes are
kept clear of sources of smells and fumes, and where
there is any possibility of pollution of the air by dust, shav-
ings etc., precautions must be taken to prevent contami-
nation.
If necessary suitable barrier rails should be provided to
prevent any combustible material being placed within
900mm of the outlets.
1.3.10 Electrical Supply
Wiring external to the air heater must be installed in accor-
dance with the I.E.E. Regulations for Electrical Installa-
tions and any local regulations which apply.
All standard heaters are supplied by 230V - 1ph, 50Hz.
The method of connection to the main electricity supply
must:-
- facilitate the complete electrical isolation of the unit(s)
- be in a readily accessible position adjacent to the unit(s)
- serve only the unit(s)
- have a contact separation of at least 3mm in all poles.
See the accompanying wiring diagram for the heater
electrical connections
OUH units can also be supplied for 400V 3N, 50Hz.
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