return air sensor is wired to the enthalpy controller (HH57AC077). See Fig. 49.

To wire the return air enthalpy sensor, perform the following:

1.Use a 2-conductor, 18 or 20 AWG, twisted pair cable to connect the return air enthalpy sensor to the enthal- py controller.

2.At the enthalpy control remove the factory-installed resistor from the (SR) and (+) terminals.

3.Connect the field-supplied RED wire to (+) spade connector on the return air enthalpy sensor and the (SR+) terminal on the enthalpy controller. Connect the BLK wire to (S) spade connector on the return air enthalpy sensor and the (SR) terminal on the enthalpy controller.

NOTE: The enthalpy control must be set to the “D” setting for differential enthalpy control to work properly.

The enthalpy control receives the indoor and return enthalpy from the outdoor and return air enthalpy sensors and provides a dry contact switch input to the RTU-MP controller. A closed contact indicates that outside air is preferred to the return air. An open contact indicates that the economizer should remain at minimum position.

Indoor Air Quality (CO2 sensor) — The indoor air quality sensor accessory monitors space carbon dioxide (CO2) levels. This information is used to monitor IAQ levels. Several types of sensors are available, for wall mounting in the space or in return duct, with and without LCD display, and in combination with space temperature sensors. Sensors use infrared technology to measure the levels of CO2 present in the space air.

The CO2 sensors are all factory set for a range of 0 to 2000 ppm and a linear mA output of 4 to 20. Refer to the instructions supplied with the CO2 sensor for electrical requirements and terminal locations. See Fig. 50 for typical CO2 sensor wiring schematic.

To accurately monitor the quality of the air in the conditioned air space, locate the sensor near a return-air grille (if present) so it senses the concentration of CO2 leaving the space. The sensor should be mounted in a location to avoid direct breath contact.

Do not mount the IAQ sensor in drafty areas such as near supply ducts, open windows, fans, or over heat sources. Allow at least 3 ft (0.9 m) between the sensor and any corner. Avoid mounting the sensor where it is influenced by the supply air; the sensor gives inaccurate readings if the supply air is blown directly onto the sensor or if the supply air does not have a chance to mix with the room air before it is drawn into the return airstream.

Wiring the Indoor Air Quality Sensor —

For each sensor, use two 2-conductor 18 AWG (American Wire Gage) twisted-pair cables (unshielded) to connect the separate isolated 24 vac power source to the sensor and to connect the sensor to the control board terminals.

To connect the sensor to the control, identify the positive (4 to 20 mA) and ground (SIG COM) terminals on the sensor. See Fig. 50. Connect the 4-20 mA terminal to terminal TB1-9 and connect the SIG COM terminal to terminal TB1-7. See Fig. 64.

IAQ Sensor

SEN J4-2

COM J4-3 24 VAC

C08462

Fig. 64 - RTU-MP / Indoor CO2 Sensor

(33ZCSENCO2) Connections

Outdoor Air Quality Sensor (PNO 33ZCSENCO2 plus weatherproof enclosure) — The outdoor air CO2 sensor is designed to monitor carbon dioxide (CO2) levels in the outside ventilation air and interface with the ventilation damper in an HVAC system. The OAQ sensor is packaged with an outdoor cover. See Fig. 52. The outdoor air CO2 sensor must be located in the economizer outside air hood.

Wiring the Outdoor Air CO2 Sensor — A dedicated power supply is required for this sensor. A two-wire cable is required to wire the dedicated power supply for the sensor. The two wires should be connected to the power supply and terminals 1 and 2.

To connect the sensor to the control, identify the positive (4 to 20 mA) and ground (SIG COM) terminals on the OAQ sensor. See Fig. 50. Connect the 4 to 20 mA terminal to 48TC’s terminal TB1-11. Connect the SIG COM terminal to 48TC’s terminal TB1-13. See Fig. 65.

OAQ Sensor/RH Sensor

SEN J4-5

COM J4-6

24 VAC

C08463

Fig. 65 - RTU-MP / Outdoor CO2 Sensor

(33ZCSENCO2) Connections

On 48TC units equipped with factory-installed Smoke Detector(s), the smoke detector controller implements the unit shutdown through its NC contact set connected to the unit’s LCTB input. The FSD function is initiated via the smoke detector’s Alarm NO contact set. The PremierLink communicates the smoke detector’s tripped status to the CCN building control. See Fig. 23 for unit smoke detector wiring.

The Fire Shutdown Switch configuration, MENU→Config→Inputs→input 5, identifies the normally open status of this input when there is no fire alarm.

48TC

47

Page 46 Page 48
Page 47
Image 47
Carrier 48TCA04---A12 appendix IAQ Sensor SEN J4-2 COM J4-3 24 VAC
Page 46 Page 48

48TCA04---A12 specifications

The Carrier 48TCA04---A12 is a high-efficiency rooftop air conditioning unit designed for commercial and industrial applications. Known for its reliability and performance, this model features advanced technologies that cater to diverse climate control needs.

One of the standout features of the Carrier 48TCA04---A12 is its excellent energy efficiency, which adheres to the stringent standards set by the U.S. Environmental Protection Agency. The unit utilizes a highly efficient scroll compressor combined with state-of-the-art heat exchanger technology, allowing it to operate with minimal energy consumption while providing powerful cooling capabilities.

The unit comes equipped with a robust and durable design, built to withstand various environmental conditions. Its weather-resistant cabinet is constructed from high-quality materials, ensuring long-lasting performance even in harsh climates. Additionally, the unit features a galvanized steel structure with a powder-coated finish, further enhancing its resistance to corrosion and wear.

In terms of technologies, the Carrier 48TCA04---A12 incorporates advanced controls that promote optimal performance. The unit supports Carrier's smart connectivity options, facilitating remote monitoring and adjustments via smart devices. This feature ensures convenient energy management and allows maintenance teams to access performance data, leading to proactive service interventions.

Another important characteristic of this unit is its quiet operation. The design includes sound-reducing insulation and a well-engineered airflow system, minimizing noise levels to create a more comfortable indoor environment. This is particularly important for commercial spaces such as offices and retail environments, where a tranquil atmosphere is critical for customer satisfaction and productivity.

The Carrier 48TCA04---A12 also offers diverse application flexibility, making it suitable for various locations, from small retail stores to large warehouses. With several tonnage options available, users can select a model that perfectly aligns with their specific cooling needs. Additionally, the unit can be easily integrated with existing HVAC systems, providing a seamless solution for upgrading or retrofitting older installations.

To sum up, the Carrier 48TCA04---A12 rooftop air conditioning unit stands out due to its exceptional energy efficiency, durable construction, advanced technology, and quiet operation, making it a reliable choice for commercial and industrial cooling solutions. Its flexibility and smart technology integrations ensure that it meets a wide range of climate control requirements effectively.
Top Page Image Contents