Technical data

14
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 lpg gas
installations but in any event no higher than
250 mm.
2.4.2.4 Natural Ventilation Openings
to Enclosures for Flued Heaters
The table below provides specific data for
each heater model as -
Where the heater(s) is in an enclosure and
in flue only 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 5 cm
2
for each kW of
rated heat input
• At low level 10 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 lpg gas
installations but in any event no higher than
250 mm.
2.4.2.5 Mechanical Ventilation to a
Plant Room or Enclosure
The table below provides specific data for
each heater model as -
In the event that the installer prefers to
mechanically ventilate the plant room or
enclosure rather than provide ventilation
openings then -
• The plant room or enclosure needs to
be mechanically ventilated at the rate
of 4.14 m
3
/h of fresh air per kW or
rated heat input.
• It is a requirement that the mechanical
ventilation shall be of the ’input’ type
with either natural or mechanical
extraction. Where mechanical
extraction is selected then the
extraction rate should be 5%-10% less
than the input rate.
• Systems of mechanical extraction with
a natural inlet shall not be used
• It is necessary to provide an automatic
means to safely inhibit heater(s)
Minimum Free Area Of
Ventilation Opening
High Level Low Level
cm
2
cm
2
12
65 65
20
106 106
30
160 160
42
213 213
50
267 267
60
320 320
72
394 394
95
527 527
120
656 656
145
787 787
MODEL
Minimum Free Area Of
Ventilation Opening
High Level Low Level
cm
2
cm
2
12
65 130
20
106 212
30
160 320
42
213 426
50
267 533
60
320 640
72
394 788
95
527 1053
120
656 1312
145
787 1574
MODEL