Carrier 50TCA04-A07 appendix

off. Heat staging will resume after a delay to allow the supply-air temperature to drop below the SATHI value.

The maximum number of stages available is dependent on the type of heat and the number of stages programmed in the CONFIG and SERVICE configuration tables. Staging will occur as follows for gas electric units, Carrier heat pumps with a defrost board, or cooling units with electric heat:

For Heating PID STAGES = 2

HEAT STAGES = 1 (50% capacity) - energize HS1. HEAT STAGES = 2 (100% capacity) - energize HS2.

For Heating PID STAGES = 3 and AUXOUT = HS3 HEAT STAGES = 1 (33% capacity if) - energize HS1 HEAT STAGES = 2 (66% capacity) - energize HS2 HEAT STAGES = 3 (100% capacity) - energize HS3

Staging will occur as follows For heat pump units with AUXOUT configured as reversing valve:

For Heating PID STAGES = 2 and AUXOUT = Reversing Valve Heat (the H3_EX_RV output will stay energized until there is a cool demand) HEAT STAGES = 1 (50% capacity) shall energize CMP1, CMP2, RVS.

HEAT STAGES = 2 (100% capacity) shall energize HS1 and HS2.

Heating PID STAGES = 3 and AUXOUT = Reversing Valve Heat (the H3_EX_RV output will stay energized until there is a cool demand)

HEAT STAGES = 1 (33% capacity if) shall energize CMP1, CMP2, RVS

HEAT STAGES = 2 (66% capacity) shall energize HS1 HEAT STAGES = 3 (100% capacity) shall energize HS2

If AUXOUT is configured for Reversing Valve Cool, then the H3_EX_RV contact will be deenergized when there is a demand for heating. The heat stages will be cycled to temper the SAT so that it will be between the SPT and the SPT + 10_F (SPT < SAT < (SPT + 10_F)) if:

S the number of heat stages calculated is zero

Sthe OAT < 55_F

S an IAQ sensor is installed

S the IAQ Minimum Damper Position > minimum damper position

Sand the SAT < SPT -10_F.

There is also a SAT tempering routine that will act as SAT low limit safety to prevent the SAT from becoming too cold should the economizer fail to close. One stage of heating will be energized if it is not in the Cooling or Free Cooling mode and the OAT is below 55_F and the SAT is below 40_F. It will deenergize when the SAT > (SPT + 10_F).

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 SPT > OCSP + 2.5 or the SPT < OHSP - 2.5 then IAQ minimum position becomes 0 and the IQMP = MDP. The IAQ mode will resume when the SPT ≤ OCSP + 1.0 and SPT ≥ OHSP - 1.0.

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.

IAQ Pre-Occupancy Purge — This function is designed to purge the space of airborne contaminants that may have accumulated 2 hours prior to the beginning of the next occupied period. The maximum damper position that will be used is temperature compensated for cold whether conditions and can be pre-empted by Temperature Compensated Start function. For pre-occupancy to occur, the following conditions must be met:

S IAQ Pre-Occupancy Purge option is enabled in the CONFIG configuration table

S Unit is in the unoccupied state S Current Time is valid

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

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