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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
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 vapor barrier all ductwork
passing through conditioned spaces. Follow latest Sheet
Metal
and
Air
Conditioning
Association (SMACNA) and Air Conditioning Contractors
Association (ACCA) minimum installation standards for
residential heating and air conditioning systems.
5. Secure
all
ducts
weatherproof, and vibration--isolate duct openings in wall
or roof according to good construction practices.
CONFIGURING UNITS FOR DOWNFLOW
(VERTICAL) DISCHARGE
WARNING
!
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. There may be more than one disconnect
switch.
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 Figure 9.)
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 (Figure 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
8
flexible
connectors
between
Contractors
National
to
building
structure.
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
accordance with latest issue of Sheet Metal and Air
Conditioning
(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.
Flash,
Horizontal Duct Covers
Basepan
Downflow
(Vertical)
Supply
Knockout
Figure 9 - - Supply and Return Duct Opening
space,
and
use
vapor
Contractors
National
51901190402
barrier
in
Association
A09076
Basepan
Downflow
(Vertical)
Return
Knockout
A09093
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