HAMWORTHY HEATING LTD
WESSEX-HE 200 BOILER
500001008/K
6
6.5 Disconnection
Facilities must be made for disconnecting the flue
pipe from each boiler for inspection and servicing
purposes. Bends with removable covers should be
fitted for inspection and cleaning purposes where
considered appropriate. Flues must be adequately
supported and protected from damage. They must
not present a risk to people in or about the building.
6.6 Flue Discharge
The flue system must ensure safe and efficient
operation of the boiler to which it is attached, protect
the combustion process from wind effects and
disperse the products of combustion to the external
air.
The flue must terminate in a freely exposed position
and be so situated as to prevent the products of
combustion entering any opening in a building.
Where the flue diameter is less than 200mm a
terminal should be fitted. Where the flue is of a larger
size consideration should be given to the fitting of a
terminal.
6.7 Surface Temperatures
Combustible materials in the vicinity of the boiler and
flue shall not exceed 65°C during boiler operation.
The flue shall not be closer than 50mm to any
combustible material, except where it passes through
such material with a non-combustible sleeve when
the air gap may not be less than 25mm.
6.8 Flue Pipe Location
The flue must not be placed or fitted where there is
undue risk of accidental damage to the flue pipe or
undue danger to persons in the vicinity.
Note!
The flue MUST be self-supporting.
7.0 AIR SUPPLY
Detailed recommendations for air supply are given in
BS 6644
Clause 19.
The following notes are intended to give general
guidance.
In all cases there MUST be provision for an adequate
supply of air for both combustion and general
ventilation,
in addition
to that required for any other
appliance.
7.1 Air Supply by Natural Ventilation
The purpose provided space housing the boiler must
have, or be provided with, permanent air vents
communicating directly with the outside air, at high
level and at low level. Where communication with the
outside air is only possible by means of high level air
vents, separate ducting down to floor level for the
lower vents should be used. For an exposed boiler
house, air vents should be fitted preferably on all four
sides, but at least on 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. Grilles
or louvres must be so designed that high velocity air
streams do not occur within the space housing the
boiler. The grilles shall have a total minimum free
area as follows -
Low Level (inlet)
-540cm
2
plus 4.5cm
2
per kilowatt in
excess of 60 kW total rated input.
High Level (outlet)
- 270cm
2
plus 2.25cm
2
per
kilowatt in excess of 60kW total rated input.
The air supplied for boiler house ventilation shall not
allow the boiler house temperature to exceed 25°C at
floor level, 32°C at mid-level and 40°C at ceiling level
during the heating season.
7.2 Air Supply by Mechanical Ventilation
The supply of air to a space housing the boiler by
mechanical means should be by mechanical inlet with
natural or mechanical extraction. Mechanical extract
ventilation with natural inlet must not be used.
The requirements of air supply by mechanical
ventilation are per 200kW module as follows: -
Inlet air - 771m
3
/h (minimum)
Extract air - 514m
3
/h
NOTE
For mechanical ventilation systems an
automatic control should be provided to cut off the
gas supply to the boiler, in the event of failure of air
flow in either inlet or extract fans.
