8
513 01 3103 00
Select and size ductwork, supply--air registers, and return air
grilles according to ASHRAE (American Society of Heating,
Refrigeration, and Air Conditioning Engineers) recommendations.
The unit has duct flanges on the supply-- and return--air openings
on the side of the unit.
When designing and installing ductwork, consider the following:
1. All units should have field--supplied filters or accessory filter
rack installed in the return --air side of the unit.
Recommended sizes for filters are shown in Table 1.
2. Avoid abrupt duct size increases and reductions. Abrupt
change in duct size adversely affects air performance.
IMPORTANT: Use flexible connectors between ductwork and unit
to prevent transmission of vibration. Use suitable gaskets to
ensure weather tight and airtight seal. When electric heat is
installed, use fireproof canvas (or similar heat resistant material)
connector between ductwork and unit discharge connection. If
flexible duct is used, insert a sheet metal sleeve inside duct. Heat
resistant duct connector (or sheet metal sleeve) must extend
24--in. (610 mm) from electric heater element.
3. Size ductwork for cooling air quantity (cfm). The minimum
air quantity for proper electric heater operation is listed in
Table 2. 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 v apor 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.
Configuring Units for Downflow (Vertical)
Discharge
FIG. 9 -- SUPPLY AND RETURN DUCT OPENINGS
Horizontal Duct Covers
Basepan
Downflow
(Vertical)
Supply
Knockout
Basepan
Downflow
(Vertical)
Return
Knockout
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or
death.
Before performing service or maintenance operations on the
system, turn off main power to unit and install lockout tag.
!
WARNING
1. Open all electrical disconnects and install lockout tag
before starting any service work.
2. Remove horizontal (metal) ductcovers to access vertical
(downflow) discharge duct knockouts in unit basepan. (See
Fig. 9.)
3. To remove downflow return and supply knockout covers,
break front and right side connecting tabs with a
screwdriver and hammer. Push cover down to break rear
and left side tabs.
NOTE: These panels are held in place with tabs similar to an
electrical knockout. Reinstall horizontal duct covers (Fig. 9)
shipped on unit from factory. Insure openings are air and
watertight.
NOTE: The design and installation of the duct system must be in
accordance with the standards of the NFPA for installation of
nonresidence--type air conditioning and ventilating systems,
NFPA 90A or residence--type, NFPA 90B; and/or local codes and
ordinances.
Adhere to the following criteria when selecting, sizing, and
installing the duct system:
1. Units are shipped for side shot installation.
2. Select and size ductwork, supply--air registers, and
return--air grilles according to American Society of Heating,
Refrigeration and Air Conditioning Engineers (ASHRAE)
recommendations.
3. Use flexible transition between rigid ductwork and unit to
prevent transmission of vibration. The transition may be
screwed or bolted to duct flanges. Use suitable gaskets to
ensure weather--tight and airtight seal.
4. All units must have field --supplied filters or accessory filter
rack installed in the return --air side of the unit.
Recommended sizes for filters are shown in Table 1.
5. Size all ductwork for maximum required airflow (either
heating or cooling) for unit being installed. Avoid abrupt
duct size increases or decreases or performance may be
affected.
6. Adequately insulate and weatherproof all ductwork located
outdoors. Insulate ducts passing through unconditioned
space, and use v apor barrier in accordance with latest
issue of Sheet Metal and Air Conditioning Contractors
National Association (SMACNA) and Air Conditioning
Contractors of America (ACCA) minimum installation
standards for heating and air conditioning systems. Secure
all ducts to building structure.
7. Flash, weatherproof, and vibration--isolate all openings in
building structure in accordance with local codes and good
building practices.
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