48TJ004-028 Single-Package Rooftop Units Electric Cooling/Gas Heating
3 to 25 Nominal Tons
Single-Package Rooftop Units with:
Alumagard heat exchanger coating
Induced-draft fan for gas combustion
Tubular heat exchangers
Galvanized steel cabinet with weather-resistant coating
Two-in. return-air filters
Commercial strength base rails (full perimeter on 004-014)
Exclusive tool less filter access door (004-014)
Corrosion resistant sloped condensate pan
Single power entry to unit
Commercial duty motors with permanently lubricated bearings
Standard cooling operation at outdoor ambient temperatures as low as 25 F
Meets ASHRAE Standard 62 (IAQ)
Exclusive integrated gas control board with diagnostics (004-014)
Features/Benefits
Compact, vertical discharge units convert to
horizontal discharge (48TJ016-028 require accessory curb or adapter),
combining installation flexibility with efficient performance
and easy maintenance.
Easy installation and conversion
All units are shipped in the vertical
discharge configuration for fit-up to standard roof curbs. All
units feature roll formed baserail design with forklift slots
on 3 sides and rigging holes for easier maneuvering. The units
can be easily converted from a vertical to a horizontal discharge
configuration either by interchanging the panels supplied with
the unit (004-014) or by using one of the horizontal supply/return
curbs or the horizontal adapter (016-028). The 48TJ004-014 units
also have a standard filter access panel, which permits tool-less
filter changes, even on units with horizontal economizers.
Integrated gas unit controller (IGC)
(004-014 only) All ignition components
are contained in the compact IGC which is easily accessible for
servicing. The IGC control board, designed and manufactured exclusively
for Carrier rooftop units, provides built in diagnostic capability.
An LED (light-emitting diode) simplifies troubleshooting by providing
visual fault notification and system status confirmation. The
IGC also contains an exclusive anti-cycle protection for gas heat
operation. After 4 continuous cycles on the unit high-temperature
limit switch, the gas heat operation is disabled, and an error
code is issued. This feature greatly improves reliability of the
rooftop unit. The IGC also contains burner control logic for accurate
and dependable gas ignition. The LED is visible without removing
the unit control box access panel. This LED fault notification
system reduces service person troubleshooting time and minimizes
service costs. The IGC also maximizes heating efficiency by controlling
evaporator fan on and off delays.
Simple electrical connections Terminal
boards, located in the base unit control box, facilitate connections
to room thermostat, outdoor thermostat(s), and economizer. Service
panels are quickly removed, permitting easy servicing. Thru the
bottom service connection capability (004-014) and thru-the-curb
service connections (016-028) allow power and control wiring to
be routed through unit basepan (004-014 units) or curb (016-028
units), minimizing roof penetrations. Both power and control connections
are made on the same side of the unit to simplify installation.
In addition, color-coded wires permit easy tracing and diagnostics.
Proven compressor reliability Design techniques feature computer programmed balance between compressor, condenser, and evaporator. Carrier specified hermetic (004-014 units) and semi-hermetic (016-028 units) compressors are equipped with compressor overcurrent and over temperature protection to ensure dependability.