andrews MAXXflo - AIR SUPPLY AND VENTILATION CONVENTIONAL FLUE SYSTEMS

MAXXo Water Heater
3131
INSTALLATION • SECTION 3
AIR SUPPLY AND VENTILATION CONVENTIONAL
FLUE SYSTEMS
e minimum effective areas of the permanent air
vents require in the compartment are as follows:
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
BS6644 and IGE/UP/10, Pt 1.
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 IGE/UP/10 Pt 1.
e permanent air vents shall be sited away from any
extract fans. Where an extract fan is tted, check for
spillage at the draught diverter as detailed in BS5440.
It may be necessary to increase the ventilation are to
compensate for the extract fan.
e vapours emitted by halogen based compounds
can, if drawn into the combustion air, cause corrosion
of the gas burner, thermocouple and storage vessel.
erefore, if heaters are to be installed in locations
where halogens are likely to be present, they should
be isolated from such compounds and ventilated from
and to outside uncontaminated atmosphere.
Some of the vulnerable areas are:
(a) Hairdressing salons and adjoining rooms and
basements
(b) Establishments where dry cleaning solutions
are used or stored
(c) Degreasing plants using hydrocarbon
solvents
(d) Premises where refrigerant gases are used or
stored
Air Vents Areas
Position of Air Vents Air from Room or Internal Space Air Direct from Outside
High Level 10cm
2
per kW Net input 5cm
2
per kW Net input
Low Level 20cm
2
per kW Net input 10cm
2
per kW Net input
Note: Both air vents must communicate with the same room or internal space or must both be on the same wall to
outside air.