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4. Installation of Air Heater(s)
4.1 General
The air heater will be delivered to site pallet mounted and
protected by plastic sheeting.
Whichever method of mounting the air heater is used the
following minimum clearances for installation and servicing
must be observed:
Right-hand side (looking at front of heater) 0.5m
Left-hand side (looking at front of heater) 0.5m
Top of burner to ceiling
1.0m
Rear of heater to nearest wall
0.4m
In order to achieve the desired performance levels it is
recommended that the installation height (floor level to base of
unit) is between 2.5m and 5.0m.
If the heater is to be base mounted it may be stood directly on
the platform, provided it is of a suitable noncombustible material
and does not extend past the front edge of the heater.
For multi-heater installations the following minimum distances
between units must be observed.
Between units, side to side
3.0m
Between units, back to back
3.0m
4.2 Fitting the Air Heater
The air heater may be installed either:
(a) Suspended by steel chains, rods or straps.
(b) On specifically designed cantilever brackets from a
non-combustible wall.
(c) On a level non-combustible surface providing the platform
does not extend past the front edge of the heater.
Whatever method of instalation is used it must be capable of
adequately supporting the weight of the unit (See Table 2) and
allowance must be made for any ancilliary equipment. Before
installing the heater any existing trusses, walls brackets etc.
must be inspected to ensure they are suitable. All supports should
be protected against corrosion.
If noise levels are of particular importance, the heater should
be isolated from the structure of the building by installing it on
suitable anti-vibration mountings.
In all such cases, and in addition, when the heater is suspended
it is essential that all oil, duct, electrical and flue connections
to the heater are made with flexible connections to maintain
continuity of connection. In the case of the flue connection
single wall stainless steel flue is deemed to flex sufficiently to
meet the requirements.
4.3 Connection of Air Heater(s) to Flue
System
The flue system connects directly into the flue socket on the
top (OUH20) or rear (OUH30 - 60) of the heater. The socket is
sized to accept standard sheet metal flue that is secured in place
using suitable fasteners.
The flue system must be fabricated with sockets facing upwards
and sound joints must be achieved by either:
(a) a close tolerance mechanical fit between sections, or
(b) the use of a suitable caulking string and cold caulking
compound.
4.4 Condensate Drainage
The design of the flue system should minimise the formation
of condensation and long external runs should be completed in
twin wall insulated flue. Where condensate and/or rain water
ingress is envisaged to be a problem a flue drain length or
condensate drain tee that drains into a gulley must be fitted.
4.3.2. General Requirements
In all cases the flue outlet socket must be connected via an
approved flue system to outside air. . If an offset is required two
sets of 45° bends may be used each set being equivalent to 0.5m
of flue length. The minimum flue length (end of flue terminal
to top of heater) shall not be less than 2.0m.
All flue ducts must be supported independently of the air heater.
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 permanent 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 resistance 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 louvres 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
3.6 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 temperatures to which they are to be
exposed during commissioning 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, shavings etc.,
precautions must be taken to prevent contamination.
If necessary suitable barrier rails should be provided to prevent
any combustible material being placed within 900mm of the
outlets.
3.7 Electrical Supply
Wiring external to the air heater must be installed in accordance
with the I.E.E. Regulations for Electrical Installations 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.
