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ENGINEERS’ SPECIFICATION GUIDE
GENERAL: Furnish and install single-package, outdoor heating
and cooling unit utilizing a rotary, reciprocating, or scroll her-
metic compressor for cooling and gas combustion for heating
duty. Unit shall discharge supply air either in downflow or hori-
zontal application as shown on the contract drawings. Unit shall
be capable of starting and running at 125 F ambient outdoor
temperature per maximum load criteria of ARI Standard 210/
240-89. Unit shall be provided with fan time-delay to prevent
cold air delivery before heat exchanger warms up. Unit shall be
provided with 30-second fan time-delay after the thermostat is
satisfied.
Nominal unit electrical characteristics shall be v,
ph, 60 Hz. The unit shall be capable of satisfactory opera-
tion within voltage limits of to v. All unit power wir-
ing shall enter unit cabinet at a single location.
COOLING CAPACITY: Total cooling capacity of the unit shall be
Btuh or greater, and sensible capacity shall be
Btuh or greater at conditions of cfm evaporator entering
air of F dry bulb, F wet bulb, and condenser en-
tering air of F dry bulb. Total design conditions shall be a
minimum of Btuh/Watt. The unit shall be capable of cool-
ing operation down to 40 F.
HEATING CAPACITY: Total heating capacity of the unit shall be
Btuh or greater with a gas input of Btuh.
CABINET: The cabinet shall be constructed of heavy duty, phos-
phated, zinc-coated, prepainted steel capable of withstanding
500 hours in salt spray. Cabinet panels shall be easily remov-
able for servicing. Unit shall be equipped with factory-supplied
condensate drain connection for evaporator coil. Indoor (evapo-
rator) blower compartment interior cabinet surfaces shall be in-
sulated with a minimum
1
⁄
2
-in. thick, flexible fiberglass
insulation, coated on the air side. Aluminum foil-faced fiberglass
insulation shall be used to meet ASHRAE standard no. 62P.
COMPRESSOR: Compressor shall be welded, fully hermetic
type with factory-installed vibration isolation. Compressor motor
shall be of the refrigerant-cooled type with line break thermal
and current overload protection. Rotary compressors shall be
standard on unit size 018. Reciprocating compressors shall be
standard on unit sizes 024-042. Scroll compressors shall be
standard on unit sizes 048 and 060.
CONDENSER SECTION: The condenser coils shall have
aluminum-plate fins mechanically bonded to seamless copper
tubes with all joints brazed. Condenser fan wheel shall be dy-
namically balanced. Fan-motor bearings shall be sealed and
permanently lubricated. Condenser-fan motor shall have inher-
ent automatic-reset thermal overload protection and shall be to-
tally enclosed.
EVAPORATOR SECTION: Evaporator coils shall have alumi-
num plate fins mechanically bonded to seamless copper tubes
with all joints brazed. Evaporator fan shall be of the forward-
curved, centrifugal, direct-driven type. Fan wheel shall be made
from steel, be double-inlet type with forward curved blades with
corrosion resistant finish and be dynamically balanced. Fan-
motor bearings shall be sealed and permanently lubricated.
Evaporator-fan motor shall have inherent automatic-reset ther-
mal overload protection and shall be open drip-proof.
HEATING SECTION: The unit shall be equipped with an
induced-draft combustion system with energy saving direct
spark ignition system and redundant main gas valve. The heat
exchanger shall be constructed of aluminized steel for corrosion
resistance. Burners shall be of the inshot type constructed of
aluminum coated steel. An integrated gas control board shall
provide control of heating and simplify troubleshooting through
its built-in diagnostics. All gas piping and electric supply shall
enter the unit cabinet at a single location.
REFRIGERANT SYSTEM: Refrigerant system shall include a
fixed orifice metering device.
CONTROLS: Unit shall be complete with self-contained control
system. Unit staging shall be minimum one-cool, one-heat. In
the event of a power failure, unit control system shall sequence
the unit to restart. Thermostat set points shall have adjustable
deadband between heat and cool. Compressors shall be pro-
vided with inherent internal line break safety feature, and also
overcurrent and overtemperature protection.
AGENCY CERTIFICATIONS AND STANDARDS: The unit shall
be UL listed and CSA certified for safety requirements. All wiring
shall be in accordance with NEC. The unit shall be rated in ac-
cordance with ARI Standards 210/240-89 and 270-84. Insula-
tion and adhesive shall meet NFPA 90A requirements for flame
spread and smoke generation.
OPTIONS: Factory-installed options shall include: base rail and
downflow application.
ACCESSORIES: Field-installed accessories shall include: flat
roof curb (8, 11, or 14 in.), pitched roof curb, modulating econo-
mizer, 2-position damper, thermostat and subbase, low-ambient
kit (Weatherprobe™ II device), natural-to-propane conversion
kit, manual outdoor-air damper, filter rack, flexible duct kit, high-
and low-pressure switches, Comprotecா kit, crankcase heater,
lifting brackets, and concentric diffuser box.
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