Carrier Weathermaster 48HJD Series Product Data page 4

Features/Benefits (cont)
Quiet, efficient operation and
dependable performance
All units are equipped with scroll
compressors which are fully hermetic
with internal vibration isolators for
extremely quiet operation. The scroll
compressors are quieter and more
reliable than reciprocating designs.
Compressors are mounted on an inde-
pendent base plate for additional
sound integrity and structural support.
Efficient condenser fan and motor
design permits operation at low sound
levels.
Totally enclosed condenser-fan
motors and permanently lubricated
bearings provide additional
dependability.
All coils use state-of-the-art inter-
nally enhanced copper tubing.
Coils are thoroughly tested with helium
particles as well as pressure tested at
the factory. Condenser coils have lou-
vered, aluminum lanced fins to provide
maximum heat transfer for optimum
efficiency and easy cleaning.
Carrier's exclusive dimpled heat
exchangers optimize heat transfer for
improved efficiency. The tubular de-
sign permits hot gases to make multi-
ple passes across the path of the sup-
ply air. In addition, dimpled heat ex-
changer tubes act as baffles, forcing
the hot gases to stay in close contact
with the cell walls to maximize heat
transfer and efficiency.
The California Air Quality Man-
agement NO requirement of
x
40 nanograms/joule or less
is met when Low NO kit
x
CRLOWNOX001A00 is installed on
004-006 sizes.
The induced draft combustion
system eliminates the unsightly ap-
pearance of flue stacks, and diminishes
the effects of winds on heating opera-
tion. The inducer fan draws hot com-
bustion gas through the heat exchang-
er at the optimum rate for the most ef-
fective heat transfer. The induced draft
also prevents contaminants from enter-
ing the supply air if a leak in the heat
exchanger occurs.
The direct spark ignition system
saves operating expense when com-
pared to old-style pilot ignition sys-
tems. No crossover tube is required,
therefore no sooting or pilot fouling
problems can occur.
4
LP conversion kit — Standard units
are designed for natural gas. An LP
Conversion Kit is available as an acces-
sory, if required. Installation of the ac-
cessory LP kit simply involves chang-
ing the gas orifices to accommodate
liquid propane gas.
Refrigerant circuit protection
assures dependability. All units have
standard:
1) loss-of-charge/low-pressure protec-
tion switch which allows operation
at lower ambient conditions while
protecting against low-charge
operation
2) freeze-protection thermostat, which
protects against evaporator coil frost
build-up
3) high-pressure switch, which protects
against above normal operating
pressure
4) filter driers, which trap moisture and
debris in the refrigeration system.
5) Carrier's exclusive Acutrol™ meter-
ing device, which precisely controls
refrigerant flow, preventing slug-
ging and floodback, while maintain-
ing optimum unit performance by
metering the circuits individually.
Two independent compressor cir-
1
cuits (all 7 / to 12 ton units) provide
2
pinpoint comfort control, improved
efficiency, and back-up capability.
Carrier controls add reliability,
efficiency, and simplification
Apollo communicating controls
can be ordered as a factory-installed
option. Designed exclusively by
Carrier, the controls can be used to
actively monitor all modes of oper-
ation as well as indoor fan status, filter
status, indoor-air quality, supply-air
temperature, and outdoor-air
temperature.
The Apollo control board is factory-
installed in the rooftop unit control box
and comes equipped with built-in diag-
nostic capabilities. Light-emitting
diodes (LEDs) simplify troubleshooting
by indicating thermostat commands for
both stages of heating and cooling,
evaporator-fan operation, and econo-
mizer operation. The Apollo communi-
cating control is designed to work spe-
cifically with Carrier TEMP and VVT
thermostats.
The standard control system is
readily adaptable to all conventional
and programmable thermostats.
Integrated gas unit controller
(IGC) — All ignition components are
contained in the compact Integrated
Gas Controller (IGC) that is easily ac-
cessible for service. The IGC, designed
exclusively by Carrier, provides built in
diagnostic capabilities. An LED simpli-
fies troubleshooting by providing visual
fault notification and system status in-
formation. The IGC board provides ex-
clusive anti-cycle protection for its gas
heat operation. The IGC also contains
burner control logic for dependable
heating operation. The LED is visible
without removing the unit control box
access panel. 48HJ units maximize
heating efficiency through the IGC's
control of evaporator fan ON/OFF de-
lays. The IGC helps make 48HJ units
reliable for many years.
Patented Cycle-LOC™ protection
system provides protection against
compressor cycling by monitoring
compressor current draw. When lack
of compressor current exists, the
Cycle-LOC circuit board locks out the
compressors. The Cycle-LOC board
may be manually reset by simply
switching thermostat to OFF, and then
back to the Cooling or AUTO modes.
No manipulation of the unit disconnect
switch is needed.
Indoor-air quality (IAQ)
The quality of building air is im-
proved as the Weathermaster
utilizes certain key features that assist
in improving indoor air quality. A
sloped condensate pan eliminates pos-
sible biological growth in the rooftop
unit. A face-split evaporator coil design
proves effective in removing additional
moisture from the supply air. Two-in.
filters are standard in all rooftop units
and an optional filter status sensor is
available.
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