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2.5 BS5440
– Up to 70kW
Open Flued Appliances installed within a Room (Natural ventilation requirements direct to Outside Air.)
Total rated net input not in excess of (70 kW
– 7 kW) x 5cm² = Ventilation opening free area Open Flued
Open Flued appliances Installed within a compartment (Natural ventilation requirements.)
Ventilation Route
Grille Location
Ventilation to room or internal space.
(The internal space ventilated into must be
ventilated as detailed above to outside air.)
Ventilation direct to outside air
Low Level (Free Area/kW)
20 cm²
10 cm²
High Level (Free
Area/kW)
10 cm²
5 cm²
Balanced Flued Appliances Installed within an Enclosure (Natural ventilation requirements)
Ventilation Route
Grille Location
Ventilation to room or internal space.
Ventilation direct to outside air
Low Level (Free Area/kW)
10 cm²
5 cm²
High Level (Free
Area/kW)
10 cm²
5 cm²
Air Vent Position
Appliance Input
(kW)
Fanned Draught
Distance (mm)
A
Above a
Terminal
0 to 7
300
>7 to 14
300
>14 to 32
300
>32
300
B
Below a
Terminal
0 to 7
300
>7 to 14
300
>14 to 32
300
>32
300
C
Horizontally to
a Terminal
0 to 7
300
>7 to 14
300
>14 to 32
300
>32
300