9
Concord CXS -
Installation & Servicing
Table 7 - CXS 70-120 boilers
Total input
Position of air
Air vent areas (air
rating of boilers
vents
direct from outside)
Up to 2 MW
HIGH LEVEL
270 cm
2
plus
2.25 cm
2
per kW
in excess of 60 kW
total rated input
Up to 2 MW
LOW LEVEL
540 cm
2
plus
4.5 cm
2
per kW
in excess of 60 kW
total rated input
Position ventilation grilles to avoid the risk of accidental
obstruction by blockage or flooding. If further guidance on
ventilation is required then consult BS.6644 and
BS.5440:2;2000
AIR SUPPLY BY MECHANICAL
VENTILATION
The supply of air by mechanical means to a space housing the
boiler should be by mechanical inlet with natural or mechanical
extraction. Mechanical extract ventilation with natural inlet must
not be used.
Where a mechanical inlet and a mechanical extract system is
applied, the design ventilation flow rates should be as in Table 4
of BS.6644.
The requirements for air supply by mechanical ventilation are given
in BS.6644.
Note.
For mechanical ventilation systems an automatic control
should be provided to cause safety shutdown or lockout of the
boiler(s) in the event of failure of air flow in either inlet or extract
fans.
IMPORTANT.
The use of an extractor fan in the same room as
the boiler (or in an adjacent, communicating room) can, in certain
conditions, adversely affect the safe operation of the boiler. Where
such a fan is already fitted (or if it is intended to fit an extractor fan
after installation of the appliance) the advice of the gas supplier
should be obtained.
GENERAL
Tests for spillage of products from the draught diverter when the
extractor fan is running and all doors and windows are shut should
be carried out after installation, If spillage is detected, the area of
permanent ventilation must be increased.
CHIMNEY SYSTEM
To ensure the safe and satisfactory operation of the boiler then
the chimney system (which may be common or individual, in the
case of twin or multiple boiler installations) must be capable of the
complete evacuation of combustion products at all times. The
effective height of the chimney terminal(s) above the boiler outlet(s)
must ensure sufficient buoyancy to overcome the resistance of
the bends, tees and runs of the flue pipe involved and shall
terminate in a down draught free zone. The number of bends and
lengths of horizontal flue pipe used should be kept to a minimum
in order to reduce gas flow resistance.
Compliance with the recommendations made in BS.6644; British
Gas publication IM 11 ‘Flues for Commercial and Industrial Gas
Fired Boilers and Air Heaters’ and the’ Third Edition of the 1956
Clean Air Act Memorandum’ should be strictly observed where
applicable.
The chimney design should avoid the formation of excessive
quantities of condensate. For this reason it is recommended that
all chimneys are insulated and lined. In the case of brick or similar
structures a stainless steel rigid or flexible flue liner (grade 304/
316) may be used in conjunction with a 50 mm (minimum) thick
layer of vemiculite or perlite granules between the liner and the
inner skin of the chimney body. Liners should be sealed at both
top and bottom.
As the
Concord
CXS
range of boilers is supplied complete with
an integral draught diverter, a diverter MUST NOT be fitted within
the chimney system.
Drainage points positioned at the bottom of all vertical chimney
sections should be provided. Drain pipes should be no less than
25 mm I.D., manufactured from acid condensate resistant material
such as stainless steel and be positioned so that pipe runs and
discharge points are not subject to the effects of frost and that flue
gases cannot leak into the boiler room.
Care should be taken to ensure the specification of the chimney is
suitable for the application by reference to the manufacturers
literature.
Caradon Plumbing Limited
can offer advice on the
design of suitable chimney systems.
GAS SUPPLY
If there is any doubt regarding the capacity of the gas meter, the
available gas pressure, the adequacy of existing service pipes or
the size required for new service pipes then the advice of the gas
supplier should be requested.
Installation pipework should be fitted and tested for gas soundness
in accordance with BS. 689:1 IGE-UP-1 for small installations
and IGE-UP-2 for large installations.
The local gas supplier must be consulted if it is necessary to employ
a gas pressure booster.
ELECTRICAL SUPPLY
WARNING.
This appliance must be efficiently earthed.
A 230 V - 50 Hz mains supply is required, fused at 5 amps.
Wiring external to the appliance MUST be in accordance with
the I.E.E. (BS. 7671) Wiring Regulations and any local
regulations which apply.
For details of connections see Frame 14.
VENTILATION
Safe, efficient and trouble-free operation of open flued gas
boilers is vitally dependent on the provision of an adequate
supply of fresh air to the room in which the appliance is
installed. Ventilation by grilles communicating to the outside air
is required. The minimum free area of these grilles must be in
accordance with Tables 6 and 7.
Table 6 - CXS 40-60 boilers installed in a room or internal space
Boiler size
Air vent free area cm
2
40
202
50
247
60
304
This air vent shall be direct to outside air or to a room or internal
space itself with an air vent to outside air of the same size.
