MITSUBISHI ELECTRIC PRH-5 - Manual (Page 53)

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3.Duct Work
(1) All series 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
weatherproofed. 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) Correctly sized filters must be fitted and there is no
provision within the unit, however the filters may be
installed in the return air.
4.Drain piping
(1) A 1 FPT condensate drain fitting is provided. The
drain pipe can be led out at the right or left side.
Under standard specifications, it is led out at the left
side and the right 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.
Duct connection with a vertical air plenum
Insulation
Singleduct
divider Duct
Duct
Roof line
Roof curb
Roof curb
Plenum
divider
Vertical air
plenum
PRH unit
B
AC
Drain trap for condensate
Note:ESP=External Static Pressure
The drain pipe
should extend
below this level.
Drain piping
Drain trap
A>70mm
B>2C
C>2XE.S.P
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