4.3
Connection of Air Heater(s) to Flue System
A single wall Tee piece is supplied with each heater and must
be fitted to the flue outlet socket on the heater. The flue
system then connects directly on to the tee.
For flue sizes
refer to Table 1, Page 2
. Horizontal runs of flue are not
permitted. If necessary a single offset using two 45° bends
can be included to avoid obstructions. The maximum equivalent
resistance of the flue system must not exceed 20pa. Details
of how to calculate the resistance of the flue to be installed
are given in Appendix A.
4.4
Condensate Drainage
The design of the flue system should minimise the formation
of condensation, however when this is envisaged to be a
problem provision should be made for condensation to flow
to a joint where it can be drained, preferably into a gully.
4.5
Gas Connection
A servicing valve and downstream union must be fitted at
the inlet to the air heater gas controls assembly to facilitate
servicing. The gas supply to the air heater must be completed
in solid pipework and be adequately supported.
Warning:
When completing the final gas connection to the
heater do not place undue strain on the gas pipework of the
heater.
4.6
Electrical Connections
All units are fully pre-wired and only require final connections
for the incoming mains supply and completion of the control
circuit (230V) via a room thermostat, time clock etc. The
electrical supply must be run to a point adjacent to the
heater and be suitably terminated to provide an isolation
point that will prevent remote activation of the unit during
servicing. The heater electrical panel is located behind the
front panel and cable entry points are provided in the adjacent
heater framework. Reference must be made to Table 4 (Page
3) to ascertain the electrical loading of the air heater(s)
being installed so that cables of adequate cross-sectional
area to safely carry that load 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.
5.
Air Distribution System
5.1
General
NCA-G ###UD models are designed for use with duct work to
more precisely define the point of air delivery, and /or provide
ducted return air or ducted fresh air inlet. All ducting must
be independently supported of the air heater. Joints and
seams of supply ducts and fittings must be securely fastened
and made airtight.
5.2
Noise Reduction
If deemed 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.
It is recommended that ducting should be connected to the
heater spigots via an airtight flexible coupling of
noncombustible material. Before fitting coupling it must be
ensured that a maximum clearance of 13mm will be maintained
between the ends of the ducting and the heater spigots.
If required sound attenuators may be fitted in inlet and
outlet ducts to reduce airborne fan noise. Materials used in
outlet sound attenuators must be capable of withstanding
100°C air temperature without any deterioration.
5.3
Room Thermostat Siting
The room thermostat should be fitted at a point which will
be generally representative of the heated area as far as
temperature is concerned. Draughty areas, areas subjected
to direct heat e.g. from the sun, and areas where the air
movement is relatively stagnant e.g. in recesses, are all
positions to be avoided for siting the thermostat.
The thermostat should be mounted about 1.5m from the
floor.
Any room thermostat, frost thermostat, time clock etc. must
be suitable for switching 230V, 5A and must be of the 'snap
action' type to minimise contact bounce.
For electrical connections of external controls see the
accompanying wiring diagram.
6.
Commissioning & Testing
6.1
Electrical Installation
Checks to ensure electrical safety must be carried out by a
competent person.
6.2
Gas Installation
The whole of the gas installation, including the meter, should
be inspected and tested for soundness and purged in accordance
with the recommendations of IM/16:1988.
6.3
Air Distribution System
The system should be checked to ensure that the installation
work has been carried out in accordance with the design
requirements.
Particular attention should be given to the correct arrangement
of delivery ducts and registers, return air ducts and grills
and general adequacy of return air paths.
For NCA-G ###UD heaters ensure that the total duct system
resistance does not exceed the available air pressure of the
equipment supplied refer to Table 2, (Page 2). If the duct
system resistance is less than the available air pressure of
the equipment supplied additional resistance must be
introduced e.g. by adjustment of duct outlet nozzles and
balancing of the duct system.
6.4
Lighting the Air Heater
6.4.1 Gas Controls Assembly - Soundness Check
1. Ensure the gas service valve at the inlet to the gas controls
assembly is shut.
2. To prove soundness of the first main safety shut-off valve
and first start gas safety shut-off valve:-
a) Connect pressure gauge to the inlet pressure test
point on the main valve block or inlet pipework.
b) Open gas service valve and allow pressure to stabilise
before shutting it again. The valves are sound if
no pressure drop is observerved. If a pressure drop
is observed do not proceed until the fault has been
rectified. Remove pressure gauge and refit sealing
screw in pressure test point.
6.4.2 Sequence Check
1. Ensure that the gas service valve is
closed
and that the
main electrical supply to the heater is switched off.
2. Check that all external controls are either "ON" or at "MAX"
3. Turn "ON" the main electrical supply and check that the
following sequence of events occurs.
i) Burner fan runs
ii) Ignition spark is heard
iii) Main gas valves open.
iv) Burner goes to lockout as there is no gas supply.
4. Switch off main electricity supply.
6.4.3 Final Adjustment
IMPORTANT:
The maxium flow and start gas flow adjustments
provided on the GM main gas block valve assembly
(Fig 2b - 4)
are not used and must not be adjusted.
1. Remove the sealing screw from the pressure test point
located on the side of the gas inlet to the burner head
and attach a pressure gauge. Remove the sample point
5
