INSTALLATION
SECTION 3
Note:
- Both air vents must communicate with the same room or internal space or must
both be on the same wall to outside air.
Where compartment air vents are open to a room or internal space, the room or internal
space must itself have a permanent air vent(s) as previously specified.
For multiple installations where the total heat input exceeds 60 kW (204,720 Btu’s/hr),
reference must be made to BS 6644. The table on p7 should be used to calculate
requirements. Detailed recommendations are given in BS 6644 Clause 19.
The following notes are intended to give general guidance.
Ventilation shall prevent the heater environment from exceeding 32°C (90°F).
The purpose provided space housing the heater(s) 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 should be used.
For an exposed building, air vents should be fitted preferable on all four sides, but on at
least two 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 or other contaminated air.
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.
NB
-
The vapours given off by halogen based compounds can, if drawn
into the combustion air, cause corrosion of the Storage Vessel and
premature failure of the thermocouple.
If water 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 listed below:-
(i)
Hairdressing salons and adjoining rooms and basements.
(ii)
Establishments where dry cleaning solutions are used or stored.
(iii)
De-greasing plants using hydrocarbon solvents.
(iv) Premises where refrigerant gases are used or stored.
(v)
Environments with dust laden atmosphere
AIR SUPPLY
IMPORTANT
8
