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.

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. 37 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 RTU-MP 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. 36. Connect the 4-20 mA terminal to RTU-MP J4-2 and connect the SIG COM terminal to RTU-MP J4-3. See Fig. 51.

IAQ Sensor

SEN J4-2

COM J4-3 24 VAC

C08462

Fig. 51 - 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. 39. 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. 37. Connect the 4 to 20 mA terminal to RTU-MP J4-5. Connect the SIG COM terminal to RTU-MP J4-6.

OAQ Sensor/RH Sensor

SEN J4-5

COM J4-6

24 VAC

C08463

Fig. 52 - RTU-MP / Outdoor CO2 Sensor

(33ZCSENCO2) Connections

Connecting Discrete Inputs

Filter Status

The filter status accessory is a field-installed accessory. This accessory detects plugged filters. When installing this accessory, the unit must be configured for filter status by setting MENU→Config→Inputs→input 3, 5, 8, or 9 to Filter Status and normally open (N/O) or normally closed (N/C). Input 8 or 9 is recommended for easy of installation. Refer to Fig. 45 and Fig. 47 for wire terminations at J5.

50TC

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Carrier 50TC Connecting Discrete Inputs Filter Status, RTU-MP / Indoor CO2 Sensor 33ZCSENCO2 Connections
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50TC specifications

The Carrier 50TC is a cutting-edge commercial rooftop unit designed for optimal performance and reliability in a variety of HVAC applications. This unit is particularly well-suited for small to medium-sized facilities that require efficient heating, ventilation, and air conditioning solutions. A hallmark of the Carrier 50TC is its impressive energy efficiency, enabling users to significantly lower their operational costs while maintaining a comfortable indoor environment.

One of the standout features of the Carrier 50TC is its advanced performance technologies. The unit employs a high-efficiency scroll compressor that enhances refrigerant management, allowing for exceptional cooling capacities while minimizing energy consumption. Additionally, the unit is equipped with variable speed fans, which further contribute to its operational efficiency. These fans adjust their speed according to the cooling demands, allowing the system to consume energy only when necessary.

The Carrier 50TC also incorporates an innovative control system that provides intelligent diagnostics and an array of customizable settings. This system helps in monitoring the unit's performance, ensuring maximum efficiency and early detection of potential maintenance issues. Users can easily integrate the unit within their existing building management systems, enhancing overall operational control and streamlining HVAC management procedures.

Durability and ease of maintenance are key characteristics of the Carrier 50TC, designed specifically to withstand harsh weather conditions while providing long-lasting performance. The unit's robust construction includes a powder-coated cabinet, which not only improves its aesthetic appeal but also protects against corrosion, ensuring longevity.

Moreover, the Carrier 50TC is designed with eco-friendliness in mind. It utilizes environmentally friendly refrigerants, aligning with modern regulations aimed at reducing the impact of HVAC systems on the environment. By choosing the Carrier 50TC, businesses can contribute to sustainability efforts while enjoying effective temperature control.

In summary, the Carrier 50TC combines energy efficiency, advanced technologies, and robust design to deliver a reliable HVAC solution for commercial applications. With its smart control system, high-efficiency components, and eco-friendly operation, the Carrier 50TC sets a standard for performance and sustainability in the commercial heating and cooling market.
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