Bryant 581B installation instructions Return Air Temperature or Enthalpy Sensor Mounting Location

ECONOMI$ER IV

ECONOMI$ER IV

CONTROLLER

GROMMET

RETURN AIR

SENSOR

RETURN DUCT (FIELD-PROVIDED)

Exhaust Set Point Adjustment

The exhaust set point will determine when the exhaust fan runs based on damper position (if accessory power exhaust is installed). The set point is modified with the Exhaust Fan Set Point (EXH SET) potentiometer. See Fig. 32. The set point represents the damper position above which the exhaust fans will be turned on. When there is a call for exhaust, the EconoMi$er IV controller provides a 45 ± 15 second delay before exhaust fan activation to allow the dampers to open. This delay allows the damper to reach the appropriate position to avoid unnecessary fan overload.

Minimum Position Control

There is a minimum damper position potentiometer on the EconoMi$er IV controller. See Fig. 32. The minimum damper position maintains the minimum airflow into the building during the occupied period.

Fig. 34 — Return Air Temperature or Enthalpy

Sensor Mounting Location

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. 21. 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$er IV controller. The set points are A, B, C, and D. See Fig. 35. The factory-installed 620-ohm jumper must be in place across terminals SR and SR+ on the EconoMi$er IV controller. See Fig. 21 and 36.

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 sen- sor with the accessory enthalpy sensor in the same mounting location. See Fig. 21. Mount the return air enthalpy sensor in the return air duct. See Fig. 34. Wiring is provided in the EconoMi$er IV wiring harness. See Fig. 27. The outdoor enthalpy changeover set point is set with the outdoor enthalpy set point potentiometer on the EconoMi$er IV con- troller. When using this mode of changeover control, turn the enthalpy set point potentiometer fully clockwise to the D setting.

Indoor Air Quality (IAQ) Sensor Input

The IAQ input can be used for demand control ventilation control based on the level of CO2 measured in the space or return air duct.

Mount the accessory IAQ sensor according to manufacturer specifications. The IAQ sensor should be wired to the AQ and AQ1 terminals of the controller. Adjust the DCV potentiome- ters to correspond to the DCV voltage output of the indoor air quality sensor at the user-determined set point. See Fig. 37.

If a separate field-supplied transformer is used to power the IAQ sensor, the sensor must not be grounded or the EconoMi$er IV control board will be damaged.

When using demand ventilation, the minimum damper posi- tion represents the minimum ventilation position for VOC (volatile organic compound) ventilation requirements. The maximum demand ventilation position is used for fully occu- pied ventilation.

When demand ventilation control is not being used, the min- imum position potentiometer should be used to set the occu- pied ventilation position. The maximum demand ventilation position should be turned fully clockwise.

Adjust the minimum position potentiometer to allow the minimum amount of outdoor air, as required by local codes, to enter the building. Make minimum position adjustments with at least 10 F temperature difference between the out- door and return-air temperatures.

To determine the minimum position setting, perform the fol- lowing procedure:

1.Calculate the appropriate mixed air temperature using the following formula:

(TO x	OA	RA
	100 ) + (TR x		) = TM
		100

TO = Outdoor-Air Temperature OA = Percent of Outdoor Air TR = Return-Air Temperature RA = Percent of Return Air TM = Mixed-Air Temperature

As an example, if local codes require 10% outdoor air dur- ing occupied conditions, outdoor-air temperature is 60 F, and return-air temperature is 75 F.

(60 x .10) + (75 x .90) = 73.5 F

2.Disconnect the supply air sensor from terminals T and T1.

3.Ensure that the factory-installed jumper is in place across terminals P and P1. If remote damper posi- tioning is being used, make sure that the terminals are wired according to Fig. 27 and that the minimum position potentiometer is turned fully clockwise.

4.Connect 24 vac across terminals TR and TR1.

5.Carefully adjust the minimum position potentiometer until the measured mixed air temperature matches the calculated value.

6.Reconnect the supply air sensor to terminals T and T1.

Remote control of the EconoMi$er IV damper is desirable when requiring additional temporary ventilation. If a field-supplied remote potentiometer (Honeywell part number S963B1128) is wired to the EconoMi$er IV controller, the minimum position of the damper can be controlled from a remote location.

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