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.