48TC
If the OAT is between DXLOCK and 68_F (DXLOCK < OAT < 68_F) and additional cooling is required, the economizer will close the to minimum position for three minutes, the economizer integrator will then be reset to 0 and begin modulating to maintain the SASP after the stage has been energized for about 90 seconds. This will allow the economizer to calculate a new ECONSR that takes into account the cooling effect that has just been turned on and not return to the value require before the cooling was added. This will prevent the economizer from causing premature off cycles of compressors while maintaining the low SAT temperature setpoint for the number of stages active. In addition to preventing compressor short cycling, by using return air across the evaporator coil just after the compressor has started allows for increased refrigerant flow rates providing for better oil return of any oil washed out during compressor
If the OAT > 68_F and OAT < SPT and the number of DX stages requested is > 0 by the staging algorithm, then ECONSR is set to its minimum value 48_F and the damper will go to 100% open.
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 AUXO output (HS3) will be energized whenever the PremierLink controller is in the occupied mode. If the MODPE is disabled then AUXO output will be energized based on the Power Exhaust Setpoint (PES) in the SETPOINT table.
Heating — The heat stages are controlled by the Heating Control Loop, which is used to calculate the desired SAT needed to satisfy the space. It will compare the SPT to the Occupied Heat Setpoint (OHSP) + the T56 slider offset (STO) when occupied and the Unoccupied Heat Setpoint (UHSP - Unoccupied Heating Deadband) if unoccupied to calculate a Staged Heat Submaster Reference (SHSR). The heat staging algorithm compares the SHSR to the actual SAT to calculate the required number of heating stages to satisfy the load. This loop runs every 40 seconds. The following conditions must be met in order for this algorithm to run:
S Indoor fan has been ON for at least 30 seconds.
S Cool mode is not active and the time guard between modes equals zero.
S Mode is occupied or the Temperature Compensated Start or Heat mode is active.
SSPT reading is available and < (OHSP + STO).
S If it is unoccupied and the SPT < (UHSP - Unoccupied Heating Deadband). The indoor fan will be turn on by the staging algorithm.
When all of the above conditions are met, the SHSR is calculated and up to 3 stages of heat will turned on and off to satisfy to maintain the SAT = SHSR. If any of the above conditions are not met, the SHSR is set to its minimum value of 35_F.
The Staged Heat Submaster Reference (SHSR) is calculated as follows:
SHSR = Heating PID function on (error) where error = (OHSP + STO) - Space Temperature
The Maximum SHSR is determined by the SATHI configuration. If the
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
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