Harry Taylor HT2000, Installation & Servicing Manual

Page: 13 / 56

13
2.9.1.2
Mechanical Ventilation to the
Heated Space.
In the event that the heated space has a
design air change of less than 0.5 air
changes per hour and that installer prefers
to mechanically ventilate the heated space
rather than provide ventilation openings then
-
•
The heated space needs to be
mechanically ventilated so that the
design air change is 0.5 air changes or
greater.
•
It is a requirement that the mechanical
ventilation shall be of the ‘input’ type
with either natural or mechanical
extraction.
•
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)
operation should mechanical air
supply fail for any reason.
2.9.2. Heaters Installed within a Plant
Room or Enclosure.
A plant room means a room housing the
heater plant and probably other items of
building service plant and would generally
have generous space for maintenance.
An enclosure is where the heater is installed
within a compartment or confined area
where space is limited.
Where heaters are installed within a plant
room or enclosure then provision for both
combustion air and air for general ventilation
will be required by means of high
and low
level ventilation openings (sections 2.3.2.1
refers to plant room applications and
sections 2.3.2.2 refers to enclosure
applications).
Alternatively the plant room or enclosure
may be mechanically ventilated (section
2.3.2.3 refers).
2.9.2.1 Natural Ventilation Openings
to Plant Rooms
For plant room applications the minimum
free area of ventilation opening shall 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.
The table in the next column provides
specific data for each heater model as -
Minimum Free Area of
ventilation opening
High Level Low Level
cm
2
cm
2
30 None 64
35 None 79
40 None 97
60 None 127
75 None 160
85 None 193
120 None 257
135 None 291
180 None 386
205 None 460
235 None 515
275 None 623
350 None 769
375 None 847
Model