11
15% of the wall height.
The low level natural ventilation opening
should be situated on an external wall and
be within 1000 mm of floor level for natural
gas and ideally at floor level for l.p.g gas
installations but in any event no higher than
250 mm.
2.4.2.2 Natural Ventilation Openings
to Plant Rooms for Flued Heaters
The table below provides specific data for
each heater model as -
Where the heater(s) is installed in a plant
room and in flue mode (ie without a positive
connection to atmosphere of combustion air
ductwork ) the minimum free area of
ventilation opening needs to be
At high level 2 cm
2
for each kW of
rated heat input
At low level 4 cm
2
for each kW of rated
heat input
The high level ventilation opening should be
sited on an external wall and positioned as
high as is practical and always within the top
15% of the wall height
The low level natural ventilation opening
should be situated on an external wall and
be within 1000 mm of floor level for natural
gas and ideally at floor level for l.p.g gas
installations but in any event no higher than
250 mm.
2.4.2.3 Natural Ventilation Openings
to Enclosures for Room Sealed
Heaters
The table below provides specific data for
each heater model as -
For enclosure applications the minimum free
area of ventilation opening will also depend
upon whether the heater(s) is installed in
room sealed mode (ie with a positive
connection to atmosphere of both flue and
combustion air).
Or with flue only (ie without the positive
connection to atmosphere of a combustion
air duct)
Where the heater(s) is installed in a plant
room and in room sealed mode (ie with a
positive connection to atmosphere of both
flue and combustion air ) the minimum free
area of ventilation opening needs to be
At high level 5 cm
2
for each kW of
rated heat input
At low level 5 cm
2
for each kW of rated
heat input
The high level ventilation opening should be
sited on an external wall and positioned as
high as is practical and always within the top
15% of the wall height
The low level natural ventilation opening
MODEL
Minimum Free Area Of
Ventilation Opening
High Level
Low Level
cm
2
cm
2
95
527
527
120
656
656
145
787
787
MODEL
Minimum Free Area Of
Ventilation Opening
High Level
Low Level
cm
2
cm
2
95
211
422
120
263
525
145
315
630
