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FACTORY-INSTALLED OPTIONS DESCRIPTION AND USAGE
Unit With Base Rail — Unit has rigging holes and an elevated
mounting frame.
SUGGESTED USE:
• Rigging holes to provide greater ease in handling. Frame to
provide elevation and structural support for horizontal
applications.
Downflow Option — Unit is shipped from factory configured for
downflow application. Unit is equipped with base rail.
SUGGESTED USE:
• To provide easy vertical ductwork connections.
FIELD-INSTALLED ACCESSORY DESCRIPTION AND USAGE
Flat Roof Curb — Consists of galvanized steel support frame in
8-, 11-, and 14-in. high designs. Provides wood nailer to attach
roof counter flashing. Insulated basepans in curbs are provided
to prevent condensation. Ductwork attaches to rails provided in
the roof curb. A gasket is provided to form an airtight and wa-
tertight seal between unit and curb. The roof curb design meets
the standards of the NRCA (National Roofing Contractors’
Association).
SUGGESTED USE:
• Slab-mounted applications when elevation of the unit above
the slab is necessary.
• Rooftop application for downflow discharge.
• Curbs are preassembled and are available for flat or pitched
roofs.
Pitched Roof Curb — Provided in ratios of 1, 2, 3, 4, 5, and 6
to 12 for use on pitched roof applications.
SUGGESTED USE:
• For when a roof curb is needed on a pitched roof.
Modulating Economizer — Economizer is available for down-
flow or horizontal applications, and is designed for easy instal-
lation. Economizer reduces energy costs and extends
equipment life by allowing the use of outdoor air to supply ‘‘free’’
cooling when conditions are favorable.
Constant ventilation is recommended for light commercial appli-
cations when the conditioned space is occupied.
The economizer is shipped complete with a damper motor and
linkage, enthalpy control, low-voltage wiring harness, and a
rainhood. Adequate wire lengths are provided (additional field-
supplied wires are not required). Horizontal economizers are
also furnished with a 2-in. disposable air filter and gasket
material.
Modulating economizer package consists of low-leakage damp-
ers with controls. The economizer will allow a fixed percentage
of outdoor ventilation air into the unit whenever the evaporator
fan is running.
SUGGESTED USE:
• Allows outdoor air to be used for ‘‘free’’ cooling whenever the
outdoor air is below the enthalpy control setting.
• To reduce energy usage. Use whenever the hours of opera-
tion at temperatures below 40 F are significant.
Two-Position Damper — In the two-position dampers, the en-
thalpy control detects when outdoor air is suitable for ‘‘free’’
cooling by measuring the outdoor-air dry bulb temperature and
humidity. Whenever the outdoor-air quality is acceptable for
‘‘free’’ cooling, the outdoor-air damper opens fully and the
return-air damper closes, allowing outdoor air to enter the
building.
SUGGESTED USE:
• Allows use of outdoor air to cool building without using com-
pressor. Damper closes when evaporator fan is off to prevent
cold backdraft, and wasted energy.
Manual Outdoor-Air Damper — Package consists of a manu-
ally adjustable damper and includes a rainhood and birdscreen.
SUGGESTED USE:
• To allow a fixed percentage of outdoor air for ventilation under
all conditions.
• The damper may be used on either downflow or horizontal air-
flow applications.
Thermostat and Subbase — These accessories provide cool-
ing control for unit. Autochangeover and manual changeover
types are available.
SUGGESTED USE:
• To operate and control unit, and to maintain desired building
temperature.
The 0° F Low Ambient Kit — Kit permits operation down to
0° F.
SUGGESTED USE:
• When mechanical cooling is required when outdoor-air tem-
perature is between 40 F and 0° F.
Natural-to-Propane Conversion Kit — Kit consists of gas ori-
fices and other hardware required to convert the unit for use
with LP (liquid propane) gas.
SUGGESTED USE:
• When natural gas cannot be obtained and liquid propane is
used as fuel.
Filter Rack — Rack features easy installation and service-
ability.
The filter rack housing is constructed of heavy-gage steel and is
fully insulated. Both sides of the filter rack are flanged for easy
installation.
SUGGESTED USE:
• Kit provides ability to locate filters inside the unit.
Flexible Duct Kit — Consists of 2 flexible UL-listed (Underwrit-
ers’ Laboratories) ducts. The duct construction includes vapor
barrier and 1-in. fiberglass insulation. The ‘‘K’’ factor is 0.23.
Each duct has a square-to-round snap adapter for attachment
to the accessory roof curb on one end, and a round clamp collar
for attachment to the concentric diffuser box on the other end.
SUGGESTED USE:
• For use with accessory roof curb and concentric box to pro-
vide an easily-installed concentric system.
Concentric Diffuser Box — Is aerodynamically designed and
equipped with a combination 4-way supply and a center return
diffuser. A special core is provided within the diffuser box to pro-
vide even 4-way distribution.
SUGGESTED USE:
• For use with accessory roof curb and concentric box to pro-
vide an easily-installed concentric system.
Crankcase Heater — Warms crankcase oil to reduce refriger-
ant migration and ensure proper compressor lubrication.
SUGGESTED USE:
• For use in applications where crankcase is subjected to low
outside temperatures. Recommended on 208/230-v, single-
phase, 024-042 units only.
Solid-State Comprotecா Device — Package consists of a con-
trol to be field-wired into the unit controls, and provides a
5-minute delay in compressor operation between cooling
cycles.
SUGGESTED USE:
• Prevents compressor short cycling when rapid compressor
cycles may be a problem.
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