Carrier 50TJ016-028 specifications EconoMi$er Switchover Control Strategy, Changeover Set Points

MECHANICAL COOLING LOCKOUT — Determine the outdoor-air temperature at which you want the mechanical cooling (compressors) to be disabled. Locate the mechanical cooling lockout (MECH CLG LOCKOUT) potentiometer. To disable this feature, turn the potentiometer counterclockwise (CCW) to the OFF position. Otherwise, set the value between 10 and 60 F. Mechanical cooling will not operate when the out- door air temperature is below this value. See Fig. 16.

DRY BULB CHANGEOVER SET UP — Determine the dry bulb changeover set point from Table 5. The settings are A, B, C and D. Locate the ECON SP potentiometer and set the dry bulb changeover set point. See Fig. 16. When the OAT is above this set point, the damper is limited to minimum position setting.

If a potentiometer fails, its setting will default to the values in Table 6.

Table 4 — EconoMi$er Switchover Control Strategy

ECONOMI$ER SWITCHOVER		SENSORS REQUIRED
STRATEGY	Outdoor Air Temperature	Outdoor Air Enthalpy	Return Air Temperature	Return Air Enthalpy
Dry Bulb	X
Single Enthalpy		X
Differential Temperature	X		X
Differential Enthalpy*		X		X

*Must be selected manually.

Table 5 — Changeover Set Points

SETTINGS	A	B	C	D
Dry Bulb (°F)	73	69	66	63
Single Enthalpy* (Btu/lb)	27	25	24	22
Differential Temperature*	2	2	2	2
(°F, Not Adjustable)
Differential Enthalpy*	1	1	1	1
(Btu/lb, Not Adjustable)
*Field-installed accessory.

Table 6 — Default Potentiometer Settings

POTENTIOMETER	DEFAULT SETTING
CO2 SP (PPM)	1,000
MECH CLG LOCKOUT	50 F
ECON SP	D
MIN POS (%)	20

	LEGEND
COM	— Common
DAT	— Discharge Air Thermistor
DM	— Damper Motor
GND	— Ground
OAH	— Outdoor-Air Enthalpy Sensor
OAT	— Outdoor-Air Temperature Sensor
POT	— Potentiometer
RAH	— Return-Air Enthalpy Sensor
RAT	— Return-Air Temperature Sensor
REM	— Remote

*OAT sensor shipped with economizer option. OAH, RAT, RAH and CO2 are field-installed accessories.

Fig. 23 — Typical EconoMi$er Sensor Wiring

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