Carrier 48TJ016-028 specifications Oat Spt, HEATING. Unit with ECONOMI$ER2, Premierlink

intothezoneThesupplyairwillmaintainthespacetempera.- turebetweentheheatingandcoolingsetpointsasindicated Fig.47.

ThePremierLinkTM will integrate the compressol_ stages with the economizer based on similar logic as the three routines listed in the previous section. The SASP will float up and down based on the error reduction calculations that compare space

temperature and space set point.

When outdoor-air temperature conditions require the econo- mizer to close for a compressor stage-up sequence, the econo- mizer control integrator is reset to zero after the stage-up se- quence is completed. This prevents the supply-tOT temperature from &'opping too quickly and creating a freeze condition that would make the compressor turn off prematurely.

The high space set point is used for DX (direct expansion) cooling control, while the economizer space set point is a c:dculated value between the heating and cooling set points.

The economizer set point will always be at least one degree below the cooling set point, allowing for a smooth transition

from mechanical cooling with economizer assist, back to

economizer cooling as the cooling set point is achieved.

The compressors may be used for initkd cooling then the PremierLink controller will modulate the economizer using an

enor reduction calculation to hold the space temperature

between the heating and cooling set points. See Fig. 47.

The controller uses the following conditions to determine economizer cooling:

• Enthalpyis Low

•SAT reading is available

•OAT reading is available

•SPT reading is available

•OAT < SPT

•Economizer Position is NOT forced

If any of the above conditions me not met, the economizer submaster reference (ECSR) is set to maximum limit and the dmnper moves to minimum position. The operating sequence

is complete. The ECSR is recalculated every 30 seconds.

If an optional power exhaust is inst:dled, as the outdoor-air dmnper opens and closes, the power exhaust fans will be energized and deenergized.

If field-installed accessory CO2 sensors are connected to

the PlemierLink control, a PID-controlled demand ventilation

strategy will begin to operate. As the CO2 level in the zone increases above the CO2 set point, the minimum position of the

dmnper will be increased proportionally. As the CO2 level decreases because of the increase in fresh all: the outdoor-air

dalnper will be proportionally closed.

HEATING. UNIT WITH ECONOMI$ER2, PREMIERLINK

CONTROL AND A ROOM SENSOR -- Every 40 seconds the controller will calculate the required heat stages (maximum of 3) to maintain supply air temperature (SAT) if the following

qualifying conditions are met:

•Indoor fan has been on for at least 30 seconds.

•COOL mode is not active.

•OCCUPIED, TEMRCOMPENSATED START or HEAT mode is active.

•SAT reading is available.

•Fire shutdown mode is not active.

If all of the above conditions m'e met, the number of heat

stages is c_dculated; otherwise the required number of heat stages will be set to 0.

If the PremierLink controller detemfines that heat stages are required, the economizer dalnper will be moved to minimum position if occupied and closed if unoccupied.

Staging should be as follows:

If Heating PID STAGES=2

•HEAT STAGES=I (75% capacity) will energize HSI

•HEAT STAGES=2 (100% capacity) will energize HS2

In order to prevent short cycling, the unit is locked into the Heating mode forat least 10 minutes when HSI is deenergized.

When HSI is energized the induced-di'aft motor is then

energized and the burner ignition sequence begins. On units equipped for two stages of heat, when additional heat is need- ed, HS2 is energized and the high-fire solenoid on the main gas

valve (MGV) is energized. When the space condition is satis- fied and HSI is deenergized the IFM stops after a 45-second time-off delay unless in the occupied mode. The fan will run

continuously in the occupied mode as lequired by nafiomd energy and fiesh air standards.

TEMPERATURE CONTROL

w75,

•_	73
w	72	..............................................."""	SET POINT
2:	71	--	TEMPERATURE
_-	70
W
o
	694
cO	68J
		TIME

NOTE: PremierLink control performs smart staging of 2 stages of DX cooling and up to 3 stages of heat.

Fig. 46 --DX Cooling Temperature

Control Example

TEMPERATURE CONTROL

75

W

QZ

73

QZ	741_	"
W				_	------ COOL		SETPOINT
Q_	72		.........
W	71 t	_	/j	X_"_H%_,_-_'-	--	TEMPERATURE
W	704		_		--	- HEAT	SETPOINT

096968 J

TIME

Fig. 47 --Economizer Temperature

Control Example

38