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heater therefore, departure from the methods of
installing flues as published in this document is in
breach of the EC Gas Appliance Directive.
4.6.2 Distances between the appliance and the concentric
flue termination must not be greater than 9.0 m. When
calculating the total length the following equivalent
length data must be taken into account:
1 elbow @ 45
E
= 1 m
1 elbow @ 90
E
= 1,5 m.
4.7
Type B Appliances
4.7.1 If the air heater is to be installed as a B type appliance
as fig.5 i.e. air for combustion to be taken from within
the space to be heated, then it must be ensured that
an adequate air supply for combustion and ventilation
is provided, in accordance with the regulations and
rules in force.
4.7.2 A horizontal distance between air heater and flue
terminal and any combustion air intake duct, must not
be in excess of 16 m.
Note:
2 Meters of vertical rise negates the resistance
imposed by 1 meter of horizontal run.
Runs exceeding 16m may be subject to condensation
forming within the flue for which provision for its
removal must be made.
Equivalent lengths of flue fittings:
Elbow @ 45
E
= 1 m
Elbow @ 90
E
= 1,5 m.
Flue terminal
#
3.0 m
4.7.3 To ensure that the allowable resistance is not
exceeded in the case of horizontal runs of flues, a
positive rise from the air heater of 1
E
i.e. 17 mm per
metre is recommended.
4.7.4 If condensation is to be avoided, flues should not pass
through cold areas or not be installed externally.
4.7.5 When mechanical ventilation is used, it shall be by
mechanical inlet with either mechanical or natural
extraction. Automatic means of control such as
interlocks must be provided. The function of other
ventilation systems in the zone where the air heater is
installed must be taken into account. At no time
should it be possible to create a negative pressure
environment in the zone, this can lead to a hazardous
situation, whereby the air heater flue may act as a
pressure relief.
4.7.6 The terminal of a vertical flue must extend at least 1 m
above a roof surface; flues must not be located where
products of combustion might enter the building.
Terminals must be fitted to all flues and ducted
combustion air inlets.
The combustion air inlet if not
used must be protected with an access guard.
Figure 7. Flue systems for appliance types
Installation as type C appliance
Installation as type B appliance
Mugro type 2000 or Burfix 100 or 130 systems must be used
Non-ducted inlet must be fitted with protection guard
