n
be alert to the potential for personal injury. Understand these signal
words: DANGER. WARNING. and CAUTION. These words are
used with the safety-alert symbol. DANGER identifies the most se-
rious hazards which will result in severe personal injury or death.
WARNING signifies hazards which could result in personal injury
or death. CAUTION is used to identify unsafe practices which may
result in minor personal injury or product and property damage.
NOTE is used to highlight suggestions which will result in en-
hanced installation, reliability, or operation.
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Before installing or servicing system, always turn off main
power to system. There may be more than one disconnect
switch. Turn off accessory heater power switch if applicable.
FIRE, EXPLOSION, ELECTRICAL SHOCK AND
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in personal injury
or unit damage.
A qualified installer or agency must use only
factory-authorized kits or accessories when modifying this
product.
PERSONAL INJURY AND ENVIRONMENTAL
HAZARD
Failure to relieve system pressure could result in personal
injury and/or death.
1. Relieve pressure and recover all refrigerant before servicing
existing equipment, and before final unit disposal. Use all
service ports and open all flow-control devices, including
solenoid valves.
2. Federal regulations require that you do not vent refrigerant
into the atmosphere. Recover during system repair or final unit
disposal.
INTRODUCTION
The 48SD unit (see Fig. 1) is a fully self-contained, combination
Category I gas heating/electric cooling unit designed for outdoor
installation (See Fig. 3 and 4 for unit dimensions). All unit sizes
have return and discharge openings for both horizontal and
downflow configurations, and are factory shipped with all
downflow duct openings covered. Units may be installed either on
a rooftop, a cement slab, or directly on the ground if local codes
permit (See Fig. 5 for roof curb dimensions).
Models with an N in the fifth position of the model number are
dedicated Low NOx units designed for California installations.
These models meet the California maximum oxides of nitrogen
(NOx) emissions requirements of 40 nanograms/joule or less as
shipped from the factory and must be installed in California Air
Quality Management Districts or any other regions in North
America where a Low NOx rule exists.
NOTE: Low NOx requirements apply only to natural gas
installations.
RECEIVING AND INSTALLATION
Step 1--Check Equipment
IDENTIFY UNIT
The unit model number and serial number are stamped on the unit
information plate. Check this information against shipping papers.
INSPECT SHIPMENT
Inspect for shipping damage while unit is still on shipping pallet. If
unit appears to be damaged or is torn loose from its anchorage, have
it examined by transportation inspectors before removal. Forward
claim papers directly to transportation company. Manufacturer is
not responsible for any damage incurred in transit. Check all items
against shipping list. Immediately notify the nearest equipment
distribution office if any item is missing. To prevent loss or damage,
leave all parts in original packages until installation.
Step 2_Provide Unit Support
For hurricane tie downs, contact distributor for details and PE
(Professional Engineering) Certificate if required.
ROOF CURB
Install accessory roof curb in accordance with instructions shipped
with curb (See Fig. 5). Install insulation, cant strips, roofing, and
flashing. Ductwork must be attached to curb.
IMPORTANT: The gasketing of the unit to the roof curb is critical
for a water tight seal. Install gasketing material supplied with the
roof curb. Improperly applied gasketing also can result in air leaks
and poor unit performance.
Curb should be level to within 1/4 in. (6.4 mm). This is necessary
for unit drain to function properly. Refer to accessory roof curb
installation instructions for additional information as required.
SLAB MOUNT
Place the unit on a solid, level concrete pad that is a minimum of 4
in. (102 mm) thick with 2 in. (51 mm) above grade (See Fig. 2). The
slab should extend approximately 2 in. (51 mm) beyond the casing
on all 4 sides of the unit. Do not secure the unit to the slab except
when rec uired by local codes.
EVAR COIL COND. COIL
c9g096
Fig. 2 - Slab Mounting Details
GROUND MOUNT
The unit may be installed either on a slab or placed directly on the
ground, if local codes permit. Place the unit on level ground
prepared with gravel for condensate discharge.
Step 3--Field Fabricate Ductwork
Secure all ducts to roof curb and building structure on vertical
discharge units. Do not connect ductwork to unit. For horizontal
applications, unit is provided with flanges on the horizontal
openings. All ductwork should be secured to the flanges. Insulate
and weatherproof all external ductwork, joints, and roof openings
with counter flashing and mastic in accordance with applicable
codes.
Ducts passing through an unconditioned space must be insulated
and covered with a vapor barrier.
If a plenum return is used on a vertical unit. the return should be
ducted through the roof deck to comply with applicable fire codes.
A minimum clearance is not required around ductwork. Cabinet
return-air static shall not exceed -.25 in. wc.
