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F. ROOFTOP INSTALLATION
1. Before locating the unit on the roof, make sure that the roof structure is adequate to
support the weight involved. (See electrical & physical tables in this book for weight
of unit.) THIS IS VERY IMPORTANT AND THE INSTALLER’S RESPONSIBILITY.
2. For rigging and roofcurb details, see Figures 14, 15, and 16.
3. The location of the unit on the roof should be such as to provide proper access for
inspection and servicing.
IMPORTANT: If unit will not be put into service immediately, block off supply and return
air openings to prevent excessive condensation.
G. DUCTWORK
The installing contractor should fabricate ductwork in accordance with local codes. Use
industry manuals as a guide when sizing and designing the duct system. Contact Air
Conditioning Contractors of America, 1513 16th St. N.W., Washington, D.C. 20036.
Place the unit as close to the conditioned space as possible allowing clearances as indi-
cated. Run ducts as directly as possible to supply and return outlets. Use of non-flam-
mable weatherproof flexible connectors on both supply and return connections at unit to
reduce noise transmission is recommended.
On ductwork exposed to outside temperature and humidity, use a minimum of 2” of
insulation and a vapor barrier. Distribution system in attic, furred space or crawl space
should be insulated with at least 2” of insulation.
1
⁄2” to 1” thick insulation is usually suffi-
cient for ductwork inside the air conditioned space.
Provide balancing dampers for each branch duct in the supply system. Properly support
ductwork from the structure.
!
WARNING
DO NOT, UNDER ANY CIRCUMSTANCES, CONNECT RETURN DUCTWORK TO
ANY OTHER HEAT PRODUCING DEVICE SUCH AS FIREPLACE INSERT,
STOVE, ETC. UNAUTHORIZED USE OF SUCH DEVICES MAY RESULT IN FIRE,
CARBON MONOXIDE POISONING, EXPLOSION, PERSONAL INJURY, OR
PROPERTY DAMAGE.
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