andrews 32/143 Installation Manual, Operation And Service Manual page 15

INSTALLATION
IMPORTANT!
1. The effective area requirements specified in the table are related to the maximum
net input of the heater(s) and are equivalent to those specified in BS 6644 and
IGE/UP/10 Pt.1.
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.
NOTE! 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 BS 6644 Clause 19.3.
and IGE/UP/10 Pt.1.
The permanent air vents shall be sited away from any extract fans. Where an extract fan is
fitted, check for spillage at the draught diverter as detailed in BS 5440 Part 1 Appendix B.
It may be necessary to increase the ventilation area to compensate for the extract fan.
4. The vapours emitted by halogen based compounds can, if drawn into the combustion
air, cause corrosion of the gas burner, thermocouple and storage vessel. Therefore, 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.
15
SECTION 3
AIR SUPPLY
AND
VENTILATION