Carrier 48TCA04---A12 appendix

When Y2 is energized, the economizer will be modulated to control to a lower supply air setpoint SASP= SATLO2

+3_F If the SAT > SASP + 5_F it will close the economizer to minimum position for 3 minutes, reset the integrator for the economizer, then start modulating the economizer to maintain the SASP after the stage two has been on for 90 seconds. This provides protection for the compressor against flooded starts and allow refrigerant flow to stabilize before modulating the economizer again. By using return air across the evaporator coil just after the compressor has started allows for increased refrigerant flow rates providing better oil return of any oil washed out during compressor start-up.

Routine No. 3: If the OAT > 68_F and the enthalpy is low and the OAT < SPT then the economizer will open to 100% and compressors 1 and 2 will be cycled based on Y1 and Y2 inputs respectively. If any of these conditions are not met the economizer will go to minimum position.

If there is no call for heating or cooling, the economizer, if available, will maintain the SASP at 70_F.

Heating — For gas or electric heat, HS1 and HS2 outputs will follow W1 and W2 inputs respectively. The fan will also be turned on if it is configured for electric heat.

Heating may also be energized when an IAQ sensor installed and has overridden the minimum economizer damper position. If the OAT < 55_F and an IAQ sensor is installed and the IAQ minimum position > minimum damper position causing the SAT to decrease below the SPT - 10_F, then the heat stages will be cycled to temper the SAT to maintain a temperature between the SPT and the SPT + 10_F.

Auxiliary Relay configured for Exhaust Fan — If the Auxiliary Relay is configured for exhaust fan (AUXOUT

=1) in the CONFIG configuration table and Continuous Power Exhaust (MODPE) is enable in the SERVICE configuration table then the output (HS3) will be energized whenever the G input is on. If the MODPE is disabled then output will be energized based on the Power Exhaust Setpoint (PES) in the SETPOINT table.

Indoor Air Quality — If the optional indoor air quality (IAQI) sensor is installed, the PremierLink controller will maintain indoor air quality within the space at the user-configured differential setpoint (IAQD) in the CONFIG configuration table. The setpoint is the difference between the IAQI and an optional outdoor air quality sensor (OAQ). If the OAQ is not present then a fixed value of 400 ppm is used. The actual space IAQ setpoint (IAQS) is calculated as follows:

IAQS = IAQD + OAQ (OAQ = 400 ppm if not present)

As air quality within the space changes, the minimum position of the economizer damper will be changed also thus allowing more or less outdoor air into the space depending on the relationship of the IAQI to the IAQS. The IAQ algorithm runs every 30 seconds and calculates IAQ minimum position value using a PID loop on the IAQI deviation from the IAQS. The IAQ minimum position is then compared against the user configured

minimum position (MDP) and the greatest value becomes the final minimum damper position (IQMP). If the calculated IAQ Minimum Position is greater than the IAQ maximum damper position (IAQMAXP) decision in the SERVICE configuration table, then it will be clamped to IAQMAXP value.

If IAQ is configured for low priority, the positioning of the economizer damper can be overridden by comfort requirements. If the SAT < SASP -8_F and both stages of heat are on for more then 4 minutes or the SAT > SASP + 5_F and both stages of cooling on for more then 4 minutes then the IAQ minimum damper position will become 0 and the IQMP = MDP. IAQ mode will resume when the SAT > SASP -8_F in heating or the SAT < SASP + 5_F in cooling.

If the PremierLink controller is configured for 1 stage of heat and cool or is only using a single stage thermostat input, this function will not work as it requires the both Y1 and Y2 or W1 and W2 inputs to be active. In this application, it is recommended that the user configure IAQ priority for high.

If IAQ is configured for high priority and the OAT < 55_F and the SAT < (SPT -10_F), the algorithm will enable the heat stages to maintain the SAT between the SPT and the SPT + 10_F.

CCN SENSOR MODE — When the PremierLink controller is configured for CCN control, it will control the compressor, economizer and heating outputs based its own space temperature input and setpoints or those received from Linkage. An optional CO2 IAQ sensor mounted in the space or received through communications can also influence the economizer and heating outputs. The PremierLink controller does not have a hardware clock so it must have another device on the CCN communication bus broadcasting time. The controller will maintain its own time once it has received time as long as it has power and will send a request for time once a minute until it receives time when it has lost power and power is restored. The controller will control to unoccupied setpoints until it has received a valid time. The controller must have valid time in order to perform any broadcast function, follow an occupancy schedule, perform IAQ pre-occupancy purge and many other functions as well. The following sections describe the operation for the functions of the PremierLink controller.

Indoor Fan — The indoor fan will be turned on whenever any one of the following conditions are met:

SIf the PremierLink controller is in the occupied mode and ASHRAE 90.1 Supply Fan is configured for Yes in the CONFIG table. This will be determined by its own internal occupancy schedule if it is programmed to follow its local schedule or broadcast its local schedule as a global schedule, or following a global schedule broadcast by another device.

S If PremierLink controller is in the occupied mode and ASHRAE 90.1 Supply Fan is configured for No and there is a heat or cool demand (fan auto mode)

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