CAUTION
UNIT DAMAGE HAZARD
Failure to follow this caution may result in damage to unit components.
When connecting ductwork to units, do not drill deeper than 3/4 in. (19.1 mm) in
shaded area shown in Fig.1 or coil may be damaged.
SLAB MOUNT - Place the unit on a solid, level concrete pad that is a minimum of 4 in. (101.6 mm) thick with 2 in.
(50.8 mm) above grade. The slab should extend approximately 2 in. (50.8 mm) beyond the casing on all 4 sides of the
unit. Do not secure the unit to the slab
except
when required by local codes.
A 6-in. (152.4 mm) wide gravel apron should be used around the flat surface to prevent airflow blockage by grass or
shrubs. The unit should be level within 1/4 in. (6.4 mm). This is necessary for the unit drain to function properly.
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 — Provide Clearances
The required minimum service clearances are shown in Base Unit Dimensions. Adequate ventilation and outdoor air
must be provided. The outdoor fan draws air through the outdoor coil and discharges it through the top fan grille. Be
sure that the fan discharge does not recirculate to the outdoor coil. Do not locate the unit in either a corner or under an
overhead obstruction. The minimum clearance under a partial overhang (such as a normal house overhang) is 48 in.
(1219 mm) above the unit top. The maximum horizontal extension of a partial overhang must not exceed 48 in. (1219
mm).
IMPORTANT
: Do not restrict outdoor airflow. An air restriction at either the outdoor-air inlet or the fan discharge may
be detrimental to compressor life. Do not place the unit where water, ice, or snow from an overhang or roof will
damage or flood the unit. Do not install the unit on carpeting or other combustible materials. Slab-mounted units
should be at least 4 in. (102 mm) above the highest expected water and runoff levels. Do not use unit if it has been
under water.
Step 4 — Select and Install Ductwork
The design and installation of the duct system must be in accordance with the standards of the NFPA for installation of
non-residence type air conditioning and ventilating systems, NFPA 90A or residence type, NFPA 90B and/or local
codes and ordinances.
Select and size ductwork, supply-air registers, and return air grilles according to ASHRAE (American Society of
Heating, Refrigeration, and Air Conditioning Engineers) recommendations. Use the duct flanges provided on the
supply-and return-air openings on the side of the unit. See Base Unit Dimensions for connection sizes and locations.
The 14-in. (356 mm) round or 14 x 20 in. (356 x 508mm) rectangular duct collars are shipped inside the unit attached
to the base pan in the indoor blower compartment. They are field-installed and
must be
removed from the indoor
blower compartment prior to start-up, even if they are not used for installation. If a corrugated shipping block is used
under the blower housing, remove and discard the block and label.
When designing and installing ductwork, consider the following:
1. All units should have field-supplied filters installed in the return-air side of the unit. Recommended sizes for
filters are shown in Physical Data table.
2. Avoid abrupt duct size increases and reductions. Abrupt change in duct size adversely affects air
performance.
3. Size ductwork for cooling air quantity (cfm). The minimum air quantity for proper electric heater operation is
listed in Table 1. Heater limit switches may trip at air quantities below those recommended.
4. Seal, insulate, and weatherproof all external ductwork. Seal, insulate and cover with a vapor barrier all
ductwork passing through conditioned spaces. Follow latest Sheet Metal and Air Conditioning Contractors
National Association (SMACNA) and Air Conditioning Contractors Association (ACCA) minimum installation
standards for residential heating and air conditioning systems.
5. Secure all ducts to building structure. Flash, weatherproof, and vibration-isolate duct openings in wall or roof
according to good construction practices.
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