Bryant 581C024--060, 581B036--072 Economi$er IV Control Modes, Outdoor Dry Bulb Changeover

581B,C

Economi$er IV Control Modes

Determine the EconoMi$er IV control mode before set up of the control. Some modes of operation may require different sensors. (See Table 6.) The EconoMi$er IV is supplied from the factory with a supply-air temperature sensor and an outdoor- air temperature sensor. This allows for operation of the EconoMi$er IV with outdoor air dry bulb changeover control. Additional accessories can be added to allow for different types of changeover control and operation of the EconoMi$er IV and unit.

Outdoor Dry Bulb Changeover

The standard controller is shipped from the factory configured for outdoor dry bulb changeover control. The outdoor-air and supply-air temperature sensors are included as standard. For this control mode, the outdoor temperature is compared to an adjustable set point selected on the control. If the outdoor-air temperature is above the set point, the EconoMi$er IV will adjust the outdoor-air dampers to minimum position. If the outdoor air temperature is below the set point, the position of the outdoor air dampers will be controlled to provide free cooling using outdoor air. When in this mode, the LED next to the free cooling set point potentiometer will be on. The changeover temperature set point is controlled by the free cooling set point potentiometer located on the control. (See Fig. 35.) The scale on the potentiometer is A, B, C, and D. See Fig. 36 for the corresponding temperature changeover values.

Table 6—Economi$er IV Sensor Usage

	ECONOMI$ER IV WITH OUTDOOR AIR
APPLICATION		DRY BULB SENSOR
		Accessories Required
Outdoor Air	None. The outdoor air dry bulb sensor
Dry Bulb		is factory installed.
Differential		CRTEMPSN002A00*
Dry Bulb
Single Enthalpy			HH57AC078
Differential			HH57AC078
					and
Enthalpy
		CRENTDIF004A00*
CO2 for DCV
Control using a		33ZCSENCO2
Wall-Mounted
CO2 Sensor
CO2 for DCV	33ZCSENCO2†			O
Control using a	and					CRCBDIOX005A00††
Duct-Mounted				R
	33ZCASPCO2**
CO2 Sensor

*CRENTDIF004A00 and CRTEMPSN002A00 accessories are used on many different base units. As such, these kits may contain parts that will not be needed for installation.

2sensor.

**33ZCASPCO2 is an accessory aspirator box required for duct-mounted applications.† 33ZCSENCO2 is an accessory CO

††CRCBDIOX005A00 is an accessory that contains both 33ZCSENCO2 and 33ZCASPCO2 accessories.

Differential Dry Bulb Control

For differential dry bulb control the standard outdoor dry bulb sensor is used in conjunction with an additional accessory dry bulb sensor (part number CRTEMPSN002A00). The accessory sensor must be mounted in the return airstream. (See Fig. 37.) Wiring is provided in the EconoMi$er IV wiring harness. (See Fig. 29.)

In this mode of operation, the outdoor-air temperature is compared to the return-air temperature and the lower temperature airstream is used for cooling. When using this mode of changeover control, turn the enthalpy setpoint potentiometer fully clockwise to the D setting. (See Fig. 35.)

Outdoor Enthalpy Changeover

For enthalpy control, accessory enthalpy sensor (part number HH57AC078) is required. Replace the standard outdoor dry bulb temperature sensor with the accessory enthalpy sensor in the same mounting location. (See Fig. 23 and 33.) When the outdoor air enthalpy rises above the outdoor enthalpy changeover set point, the outdoor-air damper moves to its minimum position. The outdoor enthalpy changeover set point is set with the outdoor enthalpy set point potentiometer on the EconoMi$er IV controller. The set points are A, B, C, and D. (See Fig. 38.) The factory-installed 620-ohm jumper must be in place across terminals SR and SR+ on the EconoMi$er IV controller. (See Fig. 23 and 39.)

Differential Enthalphy Control

For differential enthalpy control, the EconoMi$er IV controller uses two enthalpy sensors (HH57AC078 and CRENTDIF004A00), one in the outside air and one in the return air duct. The EconoMi$er IV controller compares the outdoor air enthalpy to the return air enthalpy to determine EconoMi$er IV use. The controller selects the lower enthalpy air (return or outdoor) for cooling. For example, when the outdoor air has a lower enthalpy than the return air, the EconoMi$er IV opens to bring in outdoor air for free cooling.

Replace the standard outside air dry bulb temperature sensor with the accessory enthalpy sensor in the same mounting location. (See Fig. 23.) Mount the return air enthalpy sensor in the return air duct. (See Fig. 37.) Wiring is provided in the EconoMi$er IV wiring harness. (See Fig. 29.) The outdoor enthalpy changeover set point is set with the outdoor enthalpy set point potentiometer on the EconoMi$er IV controller. When using this mode of changeover control, turn the enthalpy setpoint potentiometer fully clockwise to the D setting.

20