Bryant 551B installation instructions EconoMi$er IV Controller Potentiometer LED Locations

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 cool- ing 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. 30. The scale on the potentiometer is A, B, C, and D. See Fig. 31 for the corre- sponding temperature changeover values.

Differential Dry Bulb Control

For differential dry bulb control the standard outdoor dry bulb sensor is used in conjunction with an additional acces- sory dry bulb sensor (part number CRTEMPSN002A00). The accessory sensor must be mounted in the return airstream. See Fig. 32. Wiring is provided in the EconoMi$er IV wiring harness. See Fig. 25.

In this mode of operation, the outdoor-air temperature is compared to the return-air temperature and the lower tem- perature airstream is used for cooling. When using this mode of changeover control, turn the enthalpy set point potentiom- eter fully clockwise to the D setting. See Fig. 30.

Outdoor Enthalpy Changeover

For enthalpy control, accessory enthalpy sensor (part num- ber HH57AC078) is required. Replace the standard outdoor dry bulb temperature sensor with the accessory enthalpy sensor in the same mounting location. See Fig. 19. 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 potentiome- ter on the EconoMi$er IV controller. The set points are A, B,

Fig. 30 — EconoMi$er IV Controller Potentiometer

and LED Locations

19

	18	LED ON
				D
	17
	16		LED OFF		LED ON
						C
	15
mA	14				LED OFF			LED ON
									B
	13
	12							LED OFF		LED ON
												A
	11
	10										LED OFF
	9												100
	40	45	50	55	60	65	70	75	80	85	90	95
					DEGREES FAHRENHEIT

Fig. 31 — Outdoor Air Temperature Changeover Set Points

C, and D. See Fig. 33. The factory-installed 620-ohm jumper must be in place across terminals SR and SR+ on the EconoMi$er IV controller. See Fig. 19 and 34.

Differential Enthalpy Control

For differential enthalpy control, the EconoMi$er IV control- ler uses two enthalpy sensors (HH57AC078 and CRENTDIF004A00), one in the outside air and one in the return air duct. The EconoMi$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 loca- tion. See Fig. 19. Mount the return air enthalpy sensor in the return air duct. See Fig. 32. Wiring is provided in the EconoMi$er IV wiring harness. See Fig. 25. The outdoor

ECONOMI$ER IV

ECONOMI$ER IV

CONTROLLER

GROMMET

RETURN AIR

SENSOR

RETURN DUCT (FIELD-PROVIDED)

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 set- point potentiometer fully clockwise to the D setting.

Fig. 32 — Return Air Temperature or Enthalpy Sensor Mounting Location

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