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CTCU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL
16 of 42
SECTION 8: AIR SUPPLY
8.1 Room Sealed Installation
When installed as a room sealed heater, the air for
combustion is drawn in from outside the building. It
is important to ensure that there is adequate
ventilation to provide air for the distribution fan/s.
8.2 Open Flued Installation
It is important to ensure that there is adequate air
supply at all times for both combustion and heating
requirements in accordance with local and national
codes. When installed in this mode, the air supply to
the heater must also be fitted with a low resistance
terminal to prevent the ingress of debris. See Page
14, Figure 8.
8.2.1 Heaters Installed Within the Heated Space
Where the volume of the heated space is greater
than 4.7 m
3
per kilowatt of total rated heat input and
the air change rate is at least 0.5/h, additional high
and low level ventilation will not be required.
For a building having an air change rate less than
0.5/h, ventilation will be necessary in accordance
with local and national codes. Ventilation direct to
outside must be provided as follows:
• Heaters up to 70 kW heat input: 5.0 cm
2
per kW
of rated heat input
8.3 Building Ventilation
Where ventilation is required, air must be taken from
an outside point where it is not likely to be
contaminated or obstructed.
Where natural ventilation is used, suitable ventilation
with outside air at low level must be provided in
accordance with Section 8.2.1 and local and
national codes.
Where mechanical ventilation is used, extract rate
must be 5% - 10% less than the inlet rate. The
mechanical ventilation must be interlocked with the
burner on the heater.