Specifications

IM 1060-3 / Page 7 of 32
Table 2: 50 Hz Unit - Sheave Adjustment
Unit Size Motor HP RPM Range
Factory Motor Sheave
Settings (RPM) Position
072 1½ 756-901 786 4-Turns Open
096 1½ 720-860 858 1½-Turns Open
120 3 756-902 815 3-Turns Open
Ductwork & Attenuation
Table 3: Filter Rack/Return Air Duct Collar Dimensions
Unit Size A B C D E
072
45.12" 26.53" 3.20" 1.82" 1.50"
(1146mm) (674mm) (81mm) (46mm) (38mm)
096
55.12" 26.53" 3.20" 1.82" 1.50"
(1400mm) (674mm) (81mm) (46mm) (38mm)
120
55.12" 26.53" 3.20" 1.82" 1.50"
(1400mm) (674mm) (81mm) (46mm) (38mm)
Discharge ductwork is normally used with these conditioners.
Return air ductwork may also be required.
All ductwork should conform to industry standards of good
practice as described in the ASHRAE Systems Guide.
Thedischargeductsystemwillnormallyconsistofaexible
connector at the unit, a transition piece to the full duct size,
a short run of duct and a trunk duct teeing into a branch duct
with discharge diffusers as shown in Figure 7. The transition
piece must not have angles totaling more than 30° or severe
loss of air performance can result.
Do not connect the full duct size to the unit without using a
transition piece down to the size of the discharge collar on the
unit. With metal duct material, the sides only of the elbow and
entirebranchductshouldbeinternallylinedwithacoustic-
brousinsulationforsoundattenuation.Glassberductboard
material is more absorbing and may permit omission of the
canvas connector.
Asageneralrecommendation,theacousticbrousinsulation
should be at least 1/2 inch thick over the entire duct run (Fig-
ure 7).Forbettersoundattenuation,linethelastvediam-
eters of duct before each register with a one-inch thick sound
blanket. Elbows, tees and dampers can create turbulence or
distortionintheairow.Placeastraightlengthofduct,5to
10timestheductwidth,beforethenextttingtosmoothout
airow.Diffusersthatarelocatedinthebottomofatrunk
duct can also produce noise. For this same reason, volume
control dampers should be located several duct widths up-
stream from an air outlet.
For Hotel, Motel, Dormitory or Nursing Home applications
that use a single duct discharge, a velocity of 500 to 600 fpm
is suggested. These applications typically have static pres-
sures as low as 0.05 inches of water and duct lengths approxi-
mately six feet in length. The discharge duct must be fully
lined and have a square elbow without turning vanes. Return
airductworkcanbeconnectedtothestandardlterrack.See
Figure 4 on page 5(sidelterremovalshown).Thelter
rackcanbeinstalledforbottomlterremovalorsidelter
removalbylocatingthebrackets.Forsidelterremovalthe
brackets should be located on the bottom, left side, and top.
Forbottomlterremovalthebracketsshouldbemountedon
the left side top and right side with the spring clips supporting
thelter.
Do not use sheet metal screws directly into the unit cabinet
for connection of supply or return air ductwork, especially
return air ductwork which can hit the drain pan or the air coil.
Return air for these applications should enter through a “low”
sidewallltergrilleandrouteupthestudspacetoaceiling
plenum. For horizontal heat pumps mounted from the ceiling,
an insulated return plenum is sometimes placed at the return
air opening to further attenuate line-of-sight sound transmis-
sion through return openings.
Figure 7: Suggested Supply Ducting per ASHRAE and SMACNA Publications
Flexible Connector
Acoustic/Thermal
Lining
Two 90° Turns
(Ductwork Sized Based on Airow)
Diffuser
Diffuser
Acoustic/Thermal Lining
3ft. (.9m) to 5ft. (1.5m)
Ductwork Supported
Independent of Unit