FRESH AIR INTAKE
If required this must be fitted to the return air ducting as no special provision is made within the unit.
All fresh air intakes must be provided with air filters if they are connected to the ductwork between
the return air filter and the unit.
Consideration should be made to the return air sensor. The ducted units have a return air sensor
mounted near the return air coil. Fresh air influences may affect the room temperature. Relocating
the position of the return air sensor may be required.
AIR FILTERS
Air filters are not provided and no provision is made for fitting them within the unit as standard.
Air filters should however be provided by the installing contractor and located in an accessible location
between the return air grille and the unit. These filters must be sized for a maximum face velocity of
2.0 m/sec.
7
Where the unit must be installed in an attic space or outside, the following conditions must be
assured:
a) The unit must be protected from rain, heat and radiation by an additional layer of 1”
thick thermal insulation.
b) The return-air duct should be as short as possible, with a minimum dimension of
700x300 mm (or similar cross section) with full acoustical lining inside, and no more
than two long-radius elbows. The cross section at the duct connection to the unit shall
be equal to that of the unit.
c) The distance between the return air grille and the air intake on the unit must be as
short as possible. A minimum free passage of 0.3 m is necessary along the entire
return-air path.
d) The installation should be designed to withstand the weight of the unit and avoid
resonance vibrations. Use serrated rubber mounting under the unit and flexible joints
for the air duct.
Design and prepare in advance easy access for servicing as follows: (See Figure 4)
e) The minimum height clearance for the installation is 470 mm.
f) Allow the access to the electrical control box to facilitate its easy removal by opening
the cover (fastened by 3 screws). Allow also the access to the 700 mm long cable
which is tied inside the unit to enable relocation of the control box.
g) A distance of 200 mm must be kept between the rear side of the unit and any near-by
wall, to allow free air passage.
h) A distance of 300 mm must be kept to allow free air intake and convenient access to
air filters. Allow the access to service panels from opposite sides (right and left) for
the maintenance of fan and motor.
