5
5. Installation of the unit
Roof curb
1. The figure shows the use of the roof curb available
for mounting these units.
2. The curb should be sealed and fixed to the roof
by weather stripping.
Installation example is shown left.
4 - ø15
roof mounting holes
6 - ø15
Unit mounting holes
Unit
Roof deck
Seal with tar
Roof curb
5.1 Duct construction.
1. Series PRC units are equipped with horizontal supply and return
air openings. Duct connection to the unit should be made with duct
flanges and secured directly to the air openings with flexible duct
connectors to avoid normal noise transmission.
2. For vertical air supply, a field supply plenum should be used.
The figure below shows the recommended method for duct connection.
3. To prevent air leakage, all duct seams should be taped.
Ducts run in air spaces that are not air-conditioned must be insulated
and provided with a vapor barrier.
Ducts exposed to the outside must be weather proofed.
For quiet operation, we recommend that the insulation on the supply
duct be placed inside, lining the duct.
4. Where ducts from the outside enter a building, the duct openings
in the building should be sealed with weather stripping to prevent
rain, duct, sand, etc. from entering the building.
5. Fans will not accept any external resistance to airflow and what
provision is available if ductwork is to be fitted to the external fans.
6. Correctly sized filters must be fitted and there is no provision within
the unit, however the filters may be installed in the return air.
PRC unit
Insulation
Roof curb
Roof line
Duct
Single duct
divider
Plenum
divider
Duct
Roof curb
Duct
Duct-work length 850mm or more
Duct connection with a vertical air plenum
5.2 Lifting method.
When the unit is to be lifted and moved, attach ropes to the suspension
plates (4 p.c.s) provided on the top of the unit.
When the unit is lifted, it is center of gravity tends to shift the unit one side
and so balance, such as that in the figure below, should be attained.
The angles at which the ropes suspend the unit should be at least 60°
at the compressor end and at least 45° at the condenser end.
Care should be taken to avoid contact with the main unit while carrying.
It is necessary to protect the unit with the blanket so that the ropes
should not injure the unit.
Hook (as directly aligned over the center of gravity as possible.
An additional charge is unnecessary.
The table below shows the amount of the charge when the factory
is shipped.
5.3 Refrigerant charge
4.0
PRC-8
Refrigerant
charge per circuit
(kg)
5.9
PRC-10 PRC-12
5.7
2X4.5 2X5.9
2X5.7 3X6.3
PRC-15 PRC-20 PRC-24 PRC-32
6. Drain piping.
The drain piping should have a drain trap.
A 70mm
B 2C
C 2XE. S. P
Drain trap
Drain piping
Note: ESP = External Static Pressure
Drain trap for condensate
The drain pipe
should extend
below this level.
1. The condensate drain fitting (R1) is provided. The drain pipe can
be connected at the right or left side. Under standard specifications,
it is connected at the right side and the left side is covered.
2. The drain pipe must be provided with a trap on the outside of the unit
and also installed at an incline for proper drainage, as shown below.
3. To prevent condensate formation and leakage, provide the drain pipe
with insulation to safeguard against sweating.
4. Upon completion of the piping work, check that there is no leakage and
that the water drains off properly.
A
B
C
