Bryant 580F Indoor Air Humidity Sensor, Occupied/Unoccupied Switch, Power Exhaust

L. Indoor Air Humidity Sensor

For differential enthalpy sensing, the EconoMi$er+ control- ler uses the standard outdoor air temperature sensor, the outdoor air humidity sensor, and the optional indoor air humidity sensor, an optional return air temperature sensor (RAT). The indoor-air humidity sensor is provided with a 2-wire, 42-in. wiring harness with a 2-pin connector. The plug is installed on pins 8 and 9 on J3 of the EconoMi$er+ controller. The pins are labeled IRH and VREF on the EconoMi$er+ controller. See Fig. 22. The orange wire of the harness is connected to pin 8 (IRH). The blue wire of the har- ness is connected to pin 9 (VREF). The wiring harness should be extended with wires and wire nuts and routed from the EconoMi$er+ controller to the sensor location. The EconoMi$er+ controller compares the outdoor air enthalpy to the return air enthalpy to determine EconoMi$er+ use. The controller selects the lower enthalpy air (return or out- door) for cooling. For example, when the outdoor air has a lower enthalpy than the return air, the EconoMi$er+ control- ler opens the damper to bring in outdoor air for free cooling.

ECONOMI$ER+

ECONOMI$ER+

CONTROLLER

GROMMET

RETURN AIR

HUMIDITY SENSOR

RETURN DUCT (FIELD-PROVIDED)

Mount the return-air humidity sensor in the return-air duct. See Fig. 31.

The outdoor enthalpy changeover curve is set with at the EconoMi$er+ controller. The selectable curves are A, B, C, and D. The factory default is curve “A.” See Fig. 29. See Fig. 30 for Sensor Curve vs. Humidity.

M. Occupied/Unoccupied Switch

The EconoMi$er+ supports the use of a field-supplied occupied/unoccupied switch. When the switch is closed it pro- vides a 24-vac signal to the unit for occupied mode and when open, there is no signal to indicate unoccupied mode. The control can be configured to allow different minimum econo- mizer damper positions and to control how mechanical cool- ing will and will not be used in the occupied mode.

NOTE: The remote potentiometer (see below) will override the occupied minimum position if the potentiometer setting is greater than the occupied minimum position.

A wire from J1-OCC (pin 4) and a wire from J1-24V (pin 5) are wire-nutted together to jumper the terminals.

An occupied/unoccupied switch can be field-installed in place of the jumper to allow the user to force the control into occupied or unoccupied mode of operation for EconoMi$er+ damper position. The occupied/unoccupied switch is required if the user wants to use unoccupied free cooling or different EconoMi$er+ damper vent positions in the unoccupied mode.

N. Power Exhaust

Refer to the Accessory Power Exhaust installation instruc- tions for information on installing the power exhaust accessory.

O. Remote EconoMi$er+ Enable Control

When the control is used with energy management systems that enable and disable the EconoMi$er+, the user can install a field-supplied enable/disable switch. The switch must be wired in series with a 3K ohm, 1 watt or greater resistor. The switch is wired to terminals ORH (pin 11) and VREF (pin 12) on J3. Refer to the Start-Up section for details on how to configure the control.

P. Remote Potentiometer Occupied Minimum Position

The occupied minimum position set point remote potentiom- eter (field-supplied) is used when requiring additional tem- porary ventilation. The remote potentiometer (10K ohm - closed damper, 100K ohm - open damper) will only control the occupied minimum position.

Fig. 31 — Return Air Humidity Sensor

The accessory 5-in wiring plug, CRE+PLUG001A00 is required to connect the potentiometer.

The plug is installed on pins 15, 16 and 17 on J3 of the EconoMi$er+ controller. The pins are labeled with the ground symbol, MIN and VREF on the EconoMi$er+ control- ler. See Fig. 22. The pink wire from the harness is connected to pin 15 (ground symbol). The gray wire from the harness is connected to pin 16 (MIN). The yellow wire from the harness is connected to pin 16 (VREF). The wiring harness should be extended with wires and wire nuts and routed from the EconoMi$er+ controller to the remote potentiometer location.

NOTE: Pins 13 (ground symbol) and 14 (IAQ), which are wired to the accessory 5-pin plug, are not used for the remote potentiometer installation. They are used for an accessory IAQ sensor (if required).

The unoccupied minimum position can only be set at the controller. The occupied minimum position set point config- ured at the EconoMi$er+ controller should be set to 0 when using a remote potentiometer. The occupied minimum posi- tion will also be used as part of the IAQ routing; it will be the maximum position the damper moves to when there is an IAQ call.

If the remote potentiometer (occupied) position is greater than the EconoMi$er+ controller unoccupied minimum posi- tion, then the remote potentiometer setting will be used. The remote potentiometer is field supplied and must be a 3-wire, linear potentiometer with a resistance between 10K ohm and 100K ohm (such as the Honeywell S963B1128).

Q. Demand Ventilation Control

Demand ventilation control uses an IAQ sensor (CRE+PLUG001A00 required) to control the amount of out- side air admitted into the system. Normally, the minimum position of the EconoMi$er+ damper is established based on the demand occupancy of the space. The IAQ sensor will be used to modulate the EconoMi$er+ minimum damper position below the normal minimum position based on full occupancy. The lower limit is called the base ventilation rate. See Fig. 32.

If there is no IAQ signal the damper will be in the unoccu- pied minimum position (configuration item number 3). If there is an IAQ signal the damper will be in the occupied

—22—