Air Supply And Ventilation - Concentric And Conventional Flue Systems - andrews MAXXflo CWH30/200 Installation Manual, Operation And Maintenance Manual

AIR SUPPLY AND VENTILATION
CONCENTRIC FLUE SYSTEMS
IMPORTANT
1. The effective area requirements specified in the table
are related to the maximum heat input of the heater(s)
and are equivalent to those specified in BS6644.
2. The free area of the grilles should not be less than the
size of the recommended ventilation opening.
3. The supply of air to a space housing the heater(s) by
mechanical means should be:
(a) Mechanical inlet with natural extraction.
(b) Mechanical inlet with mechanical extraction.
NB!! NATURAL INLET WITH MECHANICAL
EXTRACTION MUST NOT BE USED
Where a mechanical inlet and mechanical extraction
system is used, the design extraction rate must not
exceed one third of the design inlet rate.
All mechanical ventilation systems must be fitted with
automatic gas shut off safety systems which cut off the
supply of gas to the heater(s) in the event of failure of
either the inlet or extract fans.
The requirements for air supply by mechanical ventilation
are given in BS6644, Clause 19.3 and in IGE/UP/10 Pt 1.
The permanent air vents shall be sited away from the
extract fans. It may be necessary to increase the
ventilation area to compensate for the extractor fan.
INSTALLATION • SECTION 3 XXXXXXXXX • SECTION XX
AIR SUPPLY AND VENTILATION
CONVENTIONAL FLUE SYSTEMS
For all installations, please refer to the table below for
calculating requirements. Detailed recommendations for
the air supply are given in BS5440, Part 2, and BS6644,
Clause 19.3 and in IGE/UP/10, Pt 1.
The following notes are provided for general
guidance only.
Ventilation shall prevent the heater environment from
exceeding 32°C (90°).
The purpose provided space in which the heater(s) are
installed must 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 must be used.
For an exposed building, air vents must be fitted on at
least two sides, preferably on all four sides.
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 space housing the
heater(s).
The grilles should have a total minimum free area for the
water heater(s), in addition to any other requirements, as
follows:
Where the heater is to be installed in a room, the
following permanent ventilation is required:
5cm 2 per kW in excess of 7kW for installations up to
54kW net.
For installations exceeding 60kW, the following
permanent ventilation is required:
Low Level (inlet) 540cm
excess of 54kW total net input
High Level (outlet) 270cm
excess of 54kW total net input
Where the heater is to be installed in a
compartment, permanent air vents are required in
the compartment at high and low level. These air
vents must either communicate with a room or
internal space or be direct to outside air.
29 29
2 plus 5cm 2 per kilowatt in
2 plus 2.5cm 2 per kilowatt in