Page 6 NVX Range Users, Instructions & Service Instructions Issue 5.5 August 2015
1.2 General Requirements
1.2.1. 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 docu-
ments.
Institution of Gas Engineers & Managers
IGE/UP/1 (Ed.2)
Strength and tightness testing and purg-
ing 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 com-
pressors 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 exceed-
ing 60kW viz. NVx10 to NVx50 inclusive and installed to
take their combustion air from within the building must be
installed in accordance with the relevant recommenda-
tions 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.
1.2.2 Location
Powrmatic NVx units are designed to operate within an
ambient temperature range of -10 to 25°C.
NVx heaters can be installed in several ways: i) suspend-
ed from ‘drop rods’ via purpose designed M10 suspension
fixing points on the heater, ii) attached to our optional wall
support brackets or iii) positioned on a level, non-combus-
tible base. In all cases, it is important that all supporting
structures have been assessed with regard to the relevant
weight loadings.
Consideration should be given to flue routes and points of
exit, gas, electrical and control connections. Consider-
ation should also be given to the throw characteristics of
the heater, issues of public access and siting of environ-
mental control stations and/or remote temperature
sensors where the position needs to be representative of
the zone temperature to which they refer.
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.
Heaters should not be installed in hazardous areas or
areas where there is a foreseeable risk of flammable or
corrosion inducing particles, gases or vapours being
drawn into the combustion air or main fan circuits.
Areas where special consideration or advice may be
required could include but is not limited to –
•
Where de-greasing solvents are present, even in
minute concentrations
•
Where paint spraying is carried out
•
Where styrenes or other laminating products are
used
•
Where airborne silicone is present
•
Where petrol engine vehicles are stored or main
tained
•
Where dust is present (i.e. wood working or
joinery shops)
•
Where high levels of extract persist
Installation in such areas may be possible under specific
conditions. Please consult our Technical Department for
further information.
1.2.2.1 Sizing of the heater
The heater should be correctly sized for the area that it is
heating, Full calculations need to be preformed to ensure
the correct KW output heater is fitted (CIBSE elemental
methodology can be used, or the Powrmatic Technical
Department can provide guidelines).
1.2.3 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
400V 3N, 50Hz.
1.2.4 Gas Supply
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.
1.2.4.1 Service Pipes
The local gas undertaking should be consulted at the
installation planning stage in order to establish the avail-
ability 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.
1.2.4.2 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.
1.2.4.3. 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.
1.2.5 Flue System
Only flue systems supplied through Powrmatic Ltd may be
used with NVx units. Several configurations of flue and
combustion air ducts are available.
Type B22 Installation,
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.
Type C12 or C32 Installation,
1.2.6 Combustion & Ventilation Air
Supply
There shall be provision for a supply of air for combustion
and, in the case of heaters installed in an enclosure or
plant room, for ventilation.
1) Installation in the heated space
In buildings with a design air change rate of 0.5 /h or
greater, additional natural or mechanical ventilation is not
necessary.
In buildings not having a design air change rate of 0.5 /h
the following apply.
Natural Ventilation
Grilles having a free area of at least 2cm² per kW of rated
heat input shall be provided at low level i.e. below the
level of the heater flue connection.
Mechanical Ventilation
Must ensure that the space air change rate is at least
0.5/h, must be of the ‘input’ type and interlocked to ensure
the heaters cannot work if the input system is not working.
2) Installation in plant rooms or enclosures
There must be permanent air vents communicating direct-
ly with the outside air, at high level and at low level.
Plant Rooms
Low level (inlet) 4cm²/kw of total rated net heat input
High level (outlet) 2cm²/kw of total rated net heat input
Enclosures
Low level (inlet) 10cm²/kw of total rated net heat input
High level (outlet) 5cm²/kw of total rated net heat input
Mechanical Ventilation
The minimum flow rate of ventilation shall be 4.14m³/h per
kilowatt of total rated heat input.
1) Installation in the heated space
No additional provision for the supply of air is necessary.
2) Installation in a plant room or enclosure
If the means of ventilation is to a room or internal space
then high and low level vents each having a free area of
10cm² per kW (net) of maximum heat input shall be fitted.
If the means of ventilation is direct to outside air then high
and low level vents each having a free area of 5cm² per
kW (net) of maximum heat input shall be fitted.