S Next Occupied Time is valid

S Time is within 2 hours of next Occupied period

S Time is within Purge Duration (user-defined 5 to 60 minutes in the CONFIG configuration table)

S OAT Reading is available

If all of the above conditions are met, the economizer damper IQMP is temporarily overridden by the pre-occupancy damper position (PURGEMP). The PURGEMP will be set to one of the following conditions based on atmospheric conditions and the space temperature:

S If the OAT ≥ NTLO (Unoccupied OAT Lockout Temperature) and OAT < 65_F and OAT is less than or equal to OCSP and Enthalpy = Low then PURGEMP = 100%.

S If the OAT < NTLO then PURGEMP = LTMP (Low Temperature Minimum Position - defaults to 10%)

S If the OAT > 65_F or (OAT ≥ NTLO and OAT > OCSP) or Enthalpy = High then PURGEMP = HTMP (High Temperature Minimum Position defaults to 35%).

The LTMP and HTMP are user adjustable values from 0 to 100% in the SETPOINT table. Whenever PURGEMP results in a number greater than 0%, the IAQ pre-occupancy purge mode will be enabled turning on the Indoor Fan Relay and setting the economizer IQMP to the PURGEMP value. When IAQ pre-occupancy mode is not active PURGEMP = 0%.

Unoccupied Free Cooling — Unoccupied free cool function will start the indoor fan during unoccupied times in order to cool the space with outside air. This function is performed to delay the need for mechanical cooling when the system enters the occupied period. Depending on how Unoccupied Free Cooling is configured, unoccupied mode can occur at any time in the unoccupied time period or 2 to 6 hours prior to the next occupied time. Once the space has been sufficiently cooled during this cycle, the fan will be stopped. In order to perform unoccupied free cooling all of the following conditions must be met:

S NTEN option is enabled in the CONFIG configuration table

S Unit is in unoccupied state S Current time of day is valid

S Temperature Compensated Start mode is not active S COOL mode is not active

S HEAT mode is not active S SPT reading is available S OAT reading is available S Enthalpy is low

SOAT > NTLO (with 1_F hysteresis) and < Max Free Cool setpoint

If any of the above conditions are not met, Unoccupied Free Cool mode will be stopped, otherwise, the mode will be controlled as follows:

The NTFC setpoint (NTSP) is determined as NTSP = (OCSP + OHSP) / 2

The Unoccupied Free Cool mode will be started when:

SPT > (NTSP + 2_F) and SPT > (OAT + 8_F)

The Unoccupied Free Cool mode will be stopped when: SPT < NTSP or SPT < (OAT + 3_F)

Temperature Compensated Start — This function will run when the controller is in unoccupied state and will calculate early start bias time (SBT) based on space temperature deviation from occupied setpoints in minutes per degree. The following conditions will be met for the function to run:

S Unit is in unoccupied state S Next occupied time is valid S Current time of day is valid

SValid space temperature reading is available (from sensor or linkage thermostat)

S Cool Start Bias (KCOOL) and Heat Bias Start (KHEAT) > 0 in the CONFIG configuration table

The SBT is calculated by one of the following formulas depending on temperature demand:

If SPT > OCSP then SBT = (SPT - OCSP) * KCOOL If SPT < OHSP then SPT = (OHSP - SPT) * KHEAT.

The calculated start bias time can range from 0 to 255 minutes. When SBT is greater than 0 the function will subtract the SBT from the next occupied time to calculate a new start time. When a new start time is reached, the Temperature Compensated Start mode is started. This mode energizes the fan and the unit will operate as though it is in occupied state. Once set, Temperature Compensated Start mode will stay on until the unit returns to occupied state. If either Unoccupied Free Cool or IAQ Pre-Occupancy mode is active when Temperature Compensated Start begins, their mode will end.

Door Switch — The Door Switch function is designed to disable mechanical heating and cooling outputs when the REMOCC contact input is closed (in the ON state) after a programmed time delay. The fan will continue to operate based on the current mode and the ASHRAE 90.1 Supply Fan setting. The delay is programmable from 2 to 20 minutes by setting the Remote Cont/Door Switch decision in the SERVICE table to a value equal to the number of minutes desired. When the contact is open (in the OFF state), the PremierLink controller will resume normal temperature control.

This application is designed for use in schools or other public places where a door switch can be installed to monitor the opening of a door for an extended period of time. The controller will disable mechanical cooling and heating when the door is open for a programmed amount of time.

This function can also be used to monitor a high condensate level switch when installed on a water source heat pump to disable mechanic cooling in case of a plugged evaporator condensate pan drain.

Linkage — The Linkage function in the PremierLink controller is available for applications using a Linkage thermostat or the 3V control system. If using the Linkage thermostat, both the PremierLink controller and the stat must be on the same CCN bus. When used as the air

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Carrier 48TCA04---A12 appendix
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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.
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