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ENGINEER’S SPECIFICATION GUIDE — OUTDOOR UNITS (Models 538A, 538C, 538D, and 538S )
GENERAL: Furnish and install a Model 538A, 538C, 538D, or
538S air-to-air outdoor unit in combination with a fan coil unit in
the location and manner shown on the plan drawings. The unit
shall be designed and tested for use with Refrigerant R-22 and
shall be equipped with refrigerant line fittings which permit
sweat or flare connections.
Nominal system electrical characteristics shall be
v,
single phase, 60 Hz. Each unit shall be capable of satisfactory
operation within voltage range of
vto v.
MAXIMUM DIMENSIONS: Outdoor unit — width
in.,
depth
in., height inches.
COOLING CAPACITY: Total system cooling capacity shall not
be less than
Btuh with indoor air quantity of
cfm at F wet bulb temperature of air entering
outdoor unit. Sensible heat capacity shall not be less than
Btuh with F dry bulb temperature. Compres-
sor power input shall be
v or less at these conditions.
HEATING CAPACITY (Heat Pump Systems Only): Total heating
capacity shall be
Btuh or greater (integrated rating)
when rated at
F dry-bulb outdoor ambient with cfm
and
F entering (heating) coil. The equipment must
have a minimum HSPF of
. Compressor shall be ca-
pable of operation in heating duty down to −20 F outdoor am-
bient air temperature (with accessory low-ambient kit). Unit shall
be capable of simultaneous heating duty and defrost cycle
operation.
OUTDOOR SECTION: The coil shall be constructed of alumi-
num plate fins mechanically bonded to copper tubing with all
joints brazed. Coil shall be
rows deep with a nominal
fin spacing of
fins per in., and shall have a face area of
not less than
square ft.
Outdoor unit shall contain a fully hermetic compressor with a
crankcase heater (non-scroll units), oil system, operating oil
charge, internal motor protection, and spring isolation. Outdoor
fans shall be direct-drive propeller type, shall discharge air hori-
zontally, shall be totally enclosed, and shall have permanently
lubricated sleeve bearings.
CONTROL CIRCUIT: Controls and protective devices shall in-
clude time-delay restart, automatic restart on power failure,
3-pole contactors (3 phase units), safety lockout if any safety is
open, high-pressure and loss-of-pressure switches, automatic
outdoor-fan motor protection, start capacitor and relay (single-
phase units without scroll compressors), system diagnostics
and high condensing temperature protection , compressor mo-
tor current and temperature overload protection, high pressure
relief, and outdoor fan failure protection. A 24-v transformer
shall be factory installed and wired on outdoor units for external
control circuit (size 018 and 024 only).
APPROVALS: Unit shall be constructed in accordance with
ASHRAE 15 (latest revision), NEC, and CSA. Unit shall carry
the UL listing label.
FIELD-INSTALLED ACCESSORIES: Low-ambient kit (538A,
538C, 538D), liquid solenoid valve, wall mount kit, crankcase
heater (reciprocating-compressor units only) and winter start kit
(538C, 538S).
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