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 also be in accordance with any relevant requirements
of the local gas region, local authority and fire authority and
the relevant recommendations of the following documents.
Institution of Gas Engineers & Managers
IGE/UP/1 (Ed.2) Strength and tightness testing and purging of
industrial and commercial gas installations.
IGE/UP/1A Soundness testing and direct purging of small low
pressure industrial and commercial gas installations.
IGE/UP/2 Gas installation pipe work, boosters and compressors
on industrial and commercial premises.
IGE/UP/10 (with Amendments October 2010) Installation gas
appliances in industrial and commercial premises.
British Standards Code of Practice
BS 5588 Fire precautions in the design and construction of
buildings.
Part 2 : 1985 Code of Practice for Shops
Part 3 : 1983 Code of Practice for Office Buildings
BS 6230 Installation of Gas Fired Forced Convection Air Heaters
for Commercial and Industrial Space Heating.
Those appliances having a gross input rating not exceeding
60kWviz. NVx10 to NVx50 inclusive and installed to take their
combustion air from within the building must be installed in
accordance with the relevant recommendations of the following
document.
BS 5440 Flues and Air Supply for gas appliances of rated input
not exceeding 60kW(1st and 2nd family gases), Part 2 - Air
Supply
For NV/D units of 10 - 50 size, reference should also be made
to
BS 5864 Code of Practice for installation of gas-fired ducted-air
heaters of rated input not exceeding 60kW.
3.2 Location
The location chosen for the air heater must permit:
- provision of a satisfactory flue system and adequate air supply.
- adequate space for servicing and air circulation around the air
heater.
IMPORTANT:
1. Heaters shall not be installed in:-
a) Those parts of spaces within buildings that have been classified
as hazardous areas as defined in BS EN 60079-10, Electrical
apparatus for explosive gas atmospheres. Classification of
hazardous areas.
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. Where only airborne particles
are present it may suffice to fit filters on the main air inlet duct
of the heater and advice may be obtained from Powrmatic Ltd.
c) Particular care should be taken to ensure chlorine vapours
(from Freon, degreaser compounds etc.) are not induced into
the combustion air stream as severe heat exchanger damage will
result.
d) In areas subjected to significant negative pressures due to
extract systems.
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.
NVx units are designed to operate within an ambient temperature
range of -10 to 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. The inlet gas
pressure under running conditions must not be less than 17.5mb.
3.3.2 Meters
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 by all connected equipment.
3.3.3. Installation Pipes
Installation pipes should be fitted in accordance with
IGE/UP/2. Pipe work 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.
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
Only flue systems supplied through Powrmatic Ltd may be used
with NVx units and they comprise of Muelink & Grol terminals
and twin to concentric adapters and SFL SUPRA straight lenghts
and elbows.
Several configurations of flue and combustion air ducts are
available (See Page 7 & 8 Figs 1a to 2b).
The flue must terminate in a freely exposed position and be
sited to prevent the products of combustion entering any opening
in a building in such concentration as to be prejudicial to health
or a nuisance.
3.5 Combustion Air Supply
Air inlet grilles shall be provided at low level when combustion
air is taken from within the space being heated and the building
has a design air change rate less than 0.5/h, and NVx units are
installed in heated spaces having a volume less than 4.7 m³/kW
of total rated heat input:-
(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
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.
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
6
4. Installation of Air Heater(s)
4.1 General
Before installation
1) Check that the local distribution conditions, nature of gas
and pressure, and adjustment of the appliance are compatible.
2) Check that the local electrical supply conditions are
compatible with the electrical data given on the data plate.
For NVx/D units the normal air flow direction is from right to
left when viewing the heater from the burner/controls end with
the fan unit upstream.
The following minimum clearances must be observed for
installation and servicing .
RHS Clearance (looking at front of heater) 1.0m
LHS Clearance (looking at front of heater) 0.2m
Top of the heater to ceiling 0.2m
Rear of heater to nearest wall 0.4m
(Depending on flue system used)
For multi air 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
Recommended mounting heights, floor level to the underside
of the unit, are:-
NVx10 - 30F 2.5m - 3m
NVx40F - 150F 3m - 5m
NVx/D Models Mounting heights not applicable
All models must not be installed at a height of less than 2.5m
to the base of the unit.
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.
When NVx modular components are used in conjunction with
the heater each component must be individually supported.
4.2 Fitting the Air Heater
Note: The access door to the controls section may be removed
to improve access. Open the door to 90°, remove the earth cable
at the bottom, and then lift the door vertically upwards to
disengage the hinge plates. Refit in reverse order. Ensure that
the earth cable is refitted.
The air heater may be installed either:
a) suspended from suitable vertical drop rods or chains.
b) on specifically designed cantilever brackets from a
noncombustible wall.
c) on a level noncombustible surface. The surface must
not extend past the front edge of NVx/F heaters.
The method of installation must be capable of adequately
supporting the weight of the unit (See Table 2, Page 3) 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.
Raise the heater up to the point of installation using suitable
and safe means and connect to the means of suspension.
Note: Each heater is provided with additional central suspension
points that can be used to provide temporary support, using
suitable means, whilst the unit is being installed. Under no
circumstances must these points be used as the final means of
suspension.
Threaded drop rods must have lock nuts fitted that are tightened
down onto the 10mm fixings in the heater.
If reducing noise levels is important the heater should be
insulated from the structure by installing it on suitable
anti-vibration mountings. In all such cases and when the heater
is suspended it is essential that all gas, duct, and electrical
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:
540 cm² plus 4.5 cm² per kilowatt in excess of 60
kW total rated input.
(b) High Level (outlet)
(1) for heaters of total rated heat input less than 60kW:
4.5cm² per kilowatt of rated heat input.
(2) for heaters of total rated heat input 60kW or more:
270 cm² plus 2.25 cm² per kilowatt in excess of 60kW
total rated input.
3.6 Air Distribution System
Where single NVx/F 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.
Afull 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
NVx/C and fan/silencer units can also be supplied for 400V3N,
50Hz.
the locking bands provided.
4.3.3.2 Vertical System - Top Outlet
1. Locate the position of the flue terminal cut a hole in the roof
to suit.
2. Fit the flashing and the flue terminal so that the lower edge
of the outer case is over the top of the flashing. Weather with
silicon sealant or similar.
Fit a condensate drain length into the flue socket on the heater
and an equivalent straight length onto the combustion air socket.
3. Fit the twin to concentric adaptor to the terminal section and
then extend down to the heater using straight lengths. Fit
adjustable lengths as the final connection pieces, to facilitate
flue disconnection for servicing. Extend the adjustable lengths
to make the final connection but do not exceed the maximum
extended length so as to maintain joint integrity.
Extend the drainage off take of the condensate drainage length
to a suitable gully or drain.
4. Ensure that internal silicon sealing rings are in place and that
all tubes are pushed fully home. Secure concentric lengths with
the locking bands provided.
4.3.3.3 Internal Combustion Air Systems
1. Complete the run of flue sections from the terminal spigot to
the flue outlet socket of the heater generally as described in
4.3.3.1 and 4.3.3.2, ensuring that the internal silicon sealing
rings are in place.
2. It is recommended that both air inlets are utilised and that
both are fitted with the mesh inlet plates supplied. In addition
a 90° bend should be fitted to the rear inlet, the inlet opening
of the bend facing to the side of the heater i.e. away from the
main air fan.
4.4 Gas Connection
A servicing valve and union to facilitate servicing must be fitted
to the gas inlet pipe work of the heater. The gas supply must be
completed in solid pipe work and be adequately supported.
Heaters suspended by drop rods, straps or chains must have a
flexible connection as the final link between the gas supply pipe
work and the heater. Sufficient slack must be left in the
connection to take account of normal movement of the heater.
Warning
When completing the final gas connection to the heater do not
place undue strain on the gas pipe work of the heater.
4.5 Electrical Connections
All units, with the exception of NVx/D units supplied with a
centrifugal fan/silencer duct section, are fully prewired and only
require final connections for the incoming mains supply and
completion of the control circuit (230V) via a room thermostat,
time clock etc. and the remote low level lockout reset.
Warning: Lockout reset is by a switched Neutral to the controls
in the heater.
All units must be earthed. See Table 4 (Page 4) to ascertain the
electrical loading of the unit(s) so that cables of adequate
cross-sectional area are used for the electrical installation. The
length of the conductors between the cord anchorage and the
terminals must be such that the current carrying conductors
become taut before the earth conductor if the cable or cord slips
out of the cord anchorage. All external controls must be of an
approved type.
See the wiring diagram accompanying these instructions.
NVx/D models supplied with a centrifugal fan/silencer duct
section require wiring to be completed between the heater and
fan. Refer to supplied wiring diagram.
NVx/D models supplied less fan must be electrically interlocked
to the air movement system so that this is started in the same
manner as the air heater fan would be viz. A connection from
the heater terminal marked “Live Main Fan” must be made to
one side of the fan motor contactor coil, the other side of the
coil being connected to Neutral. The fan motor electrical supply
must not be taken direct from the internal wiring of the NVx
heater.
connections to the heater are made with flexible connections to
maintain continuity of connection.
4.3 Flue/Combustion Air Duct System
The minimum distance between surfaces of the flue pipe and
any surfaces made from combustible materials is 300mm. If it
is necessary for the flue pipe to bass through a structure made
from combustible materials a metal sleeve must be used so that
the minimum clearance of 300mm is maintained. The flue and
combustion air ducts supplied with the heater are capable of
withstanding their own weight over the allowable flue lengths.
Wall bands and bracing brackets, or equivalent, must be used
to provide lateral stability and should be used at centres not
exceeding 2.5 metres.
All models are supplied as standard with a rear flue outlet and
the flue outlet and combustion air sockets temporarily fitted.
4.3.1.1. Conversion to Top Flue Outlet
1. Remove the two blanking plates from the flue /combustion
air openings at the top of the unit.
2. Remove the four screws from the exhaust fan outlet flange.
3. Remove the screws securing the fan mounting box to the
exhaust header plate.
4. Remove fan assembly and rotate the assembly 90°
anticlockwise.
5 Refit the fan assembly to the exhaust header plate ensuring
that the gasket is not damaged, if necessary replace or make
good with silicon sealant.
6. Secure the exhaust fan outelt flange to the underside of the
top panel and fit the blanking plates to the rear panel.
4.3.1.2 Fitting Flue/Combustion Air Sockets
1. Apply a bead of silicon sealant around the face of the flange
on the exhaust fan outlet tube that can be seen from the outside
of the heater. Place the flue socket on the outside of the heater
to mate with this flange and clamp the two flanges together, on
either side of the heater panel using the screws provided. Ensure
that the silicon sealant has sealed between the two flanges.
2. Apply a bead of silicon sealant around the face of the flange
of the combustion air socket, on the same side as the socket.
Passing the socket through the panel from the inside, position
the flange up against the panel. Secure, from the outside, with
the screws provided.
3. If ducted combustion air is not required (see Section 3.5) fit
the mesh inlet plate behind the unused combustion air inlet hole.
4. Apply silicon sealant and refit blanking plates as required to
seal unused panel holes.
4.3.2. General Requirements
See Figures 1a to 2b for the different types of flue installation.
In all cases the flue outlet socket must be connected via the
provided flue system to outside air. The maximum permitted
length of flue system is 6m, or 12m if the flue outlet only is
used. If an offset is required two sets of 45° bends should be
used each set being equivalent to 0.5m of flue length. 90° bends
may be used but each set will be equivalent to 1.0m of flue
length. The minimum flue length (end of flue terminal to back
or top of heater) shall not be less than 1.0m for the NVx10 - 50
and 1.3m for the NVx60 - 140.
All outer joints must be finished with the provided locking
bands. A smear of silicon grease to the inside of sockets will
assist in fitting components together. All flue and combustion
air ducts must be supported independently of the air heater. The
flue or flue/combustion air terminal must not be installed so as
to be less than:
- 300mm below an opening e.g. window, air brick etc.
- 200mm below eaves or gutter.
- 300mm from an internal or external corner.
- 1200mm from a surface facing the terminal.
- 1500mm vertically from another terminal on the same wall.
- 300mm horizontally from another terminal on the same wall.
- 2000mm from ground level.
4.3.3 Installation of Flue System
Note: A terminal guard, as supplied by Powrmatic Ltd, must be
fitted to horizontal flue terminals. The minimum flue length in
all cases is
4.3.3.1 Horizontal System - Rear Outlet
Note: If the outlet is required to the side of the unit 90° bends
may be fitted directly onto the inlet/outlet spigots on the heater.
1. Locate the position of the flue terminal, allowing for a slight
gradient running down from the heater to the terminal of 2° -
3° and cut a hole to suit.
2. Fit the flue terminal, securing via the wall plate and weather
with silicon sealant or similar.
3. Fit the twin to concentric adaptor to the terminal section and
extend the flue and combustion air ducts to the heater using
straight lengths. Fit an adjustable length prior to the unit, to
facilitate flue disconnection for servicing. Extend the adjustable
lengths to make the final connection to the appropriate heater
inlet/outlet spigots.
4. Ensure that internal silicon sealing rings are in place and that
all tubes are pushed fully home. Secure concentric lengths with
