GENERAL DESCRIPTION
Model PCA and DCA.
These cooling only 100% outside-air units may be roof
mounted on a factory supplied roof curb, slab mounted,
or installed on post and rails. Air is drawn into the
outside air intake located on the end of the unit and
through metal mesh filters before entering the
evaporator coil.
Every unit is charged with refrigerant and run tested
before shipment.
Unpacking
When received, the unit should be checked for damage
that might have occurred in transit. If damage is found, it
should be noted on the carrier’s Freight Bill. Request for
inspection by carrier’s agent should be made in writing at
once.
Codes and Ordinances
Local authorities having jurisdiction should be consulted
before installations are made to verify local codes and
installation procedures.
All field wiring to the unit must be done in accordance
with these instructions, the National Electric Code
(ANSI/NFPA 70-1981) in the United States and all local
codes and ordinances.
Installation should be done by a qualified agency in
accordance with the instructions in this manual and in
compliance with all codes and requirements of
authorities having jurisdiction.
UNIT LOCATION
Unit Location
An intake louver protects the service end and clearance
at this point should be maintained. A 36" clearance must
be allowed for access to the compressor and electrical
panel. A 24" clearance must be maintained for the air
inlet to the condenser coil(s).
Do not locate the unit under an overhang that will short
circuit hot air to the coil intakes.
When installed at ground level, the unit should be
mounted on a level concrete slab which should extend at
least 2" beyond the unit on all sides. The top of the slab
should be 2" above the ground level. The depth of the
slab below the ground level and its structural design is
governed by the type of soil and climatic conditions. The
slab must not be in contact with any part of the building
wall or foundation. The space between the slab and
building wall prevents the possibility of transmitting
vibration to the building.
The dimensions of the slab or roof mount should be
checked and verified before the equipment arrives. Unit
supports, roof
opening, roof curb flashing, drain requirements, and
electric locations are important to a good installation.
When installing the equipment on top of a building, the
following should be considered:
Structural members supporting the unit must be
sufficiently strong for the weight of the unit and mounting
rails.
Locate the unit as near as possible to the center of the
area to be environmentally controlled. Sufficient
clearance must be available for service, edge of roof,
other units, or hazards.
The condenser air inlet and discharge air must be
unobstructed by overhang, walls, or other equipment.
Avoid locations next to exhaust fans or flues.
Select a location where external water drainage cannot
collect around the unit.
Locate the unit so roof runoff water does not pour
directly on the unit. Provide gutter or other shielding at
roof level.
Where snowfall is anticipated, mount the unit above the
maximum snow depth for the area.
INSTALLATION
The installation of packaged units consists of making
final connections between the unit and building
services such as electrical power supply, natural gas,
supply and return duct connections, and drain
connections.
The internal systems of the unit are completely factory
installed and tested prior to shipment and no additional
field labor is required.
Setting the Unit
UNIT LOCATION
CAUTION: Units may look identical but have
significant internal differences. Check specific unit
location carefully (referring to plans if necessary) prior
to setting unit.
CURB INSTALLATION
Proper installation requires that the roof mounting curb
be firmly and permanently attached to the roof
structure. Check for adequate fastening method prior
to setting rooftop unit on curb.
PROTRUSIONS
Inspect curb to insure that none of the utility services
(electric, gas, drain lines) routed through the curb
protrude above the curb. Duct connections will
normally be made after unit is set on curb. If duct is
prefabricated and installed within the curb prior to
setting unit, insure that ductwork does not protrude
above curb.
DO NOT ATTEMPT TO SET UNIT ON CURB IF
PROTRUSIONS EXIST.
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