andrews MAXXflo - Alternative Flue Systems - CWH 30; Standard Flue System Dimensions - CWH 30; Air Supply and Ventilation - Concentric and Conventional Flue Systems

MAXXo Water Heater
3030
AIR SUPPLY AND VENTILATION CONCENTRIC FLUE
SYSTEMS
IMPORTANT
1. e effective area requirements specied in the table are
related to the maximum heat input of the heater(s) and
are equivalent to those specied in BS 6644.
2. e free area of the grilles should not be less than the
size of the recommended ventilation opening.
3. e 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.
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 tted 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.
e requirements for air supply by mechanical ventilation
are given in BS6644 and in IGE/UP/10 Pt 1.
e 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.
Where the heater is to be installed in a
compartment, permanent air vents are required
in the compartment at high and low level. ese
air vents must either communicate with a room
or internal space or be direct to outside air.
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 and
in IGE/UP/10, Pt 1.
e following notes are provided for general guidance only.
Ventilation shall prevent the heater environment
from exceeding 32°C (90°).
e 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 oor level
for the lower vents must be used.
For an exposed building, air vents must be tted 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 ooded, or in any position adjacent to an
extraction system which is carrying ammable vapour.
Grilles or louvres should be so designed that high velocity
air streams do not occur within the space housing the
heater(s).
e 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
2
plus 5cm
2
per kilowatt in
excess of 54kW total net input
High Level (outlet) 270cm
2
plus 2.5cm
2
per kilowatt in
excess of 54kW total net input
SECTION 3 • INSTALLATION