Carrier 50HJQ004 Installation, Start-Up And Service Instructions Manual page 31

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.)
Fig. 35 --- EconoMi$er IV Controller Potentiometer
and LED Locations
Outdoor Enthalpy Changeover
For enthalpy control, accessory enthalpy sensor (part number
HH57AC078) is required. Replace the standard outdoor dry bulb
temperature sensor with the accessory enthalpy sensor in the same
mounting location. (See Fig. 22.) When the outdoor air enthalpy
rises above the outdoor enthalpy changeover set point, the
outdoor-air damper moves to its minimum position. The outdoor
enthalpy changeover set point is set with the outdoor enthalpy set
point potentiometer on the EconoMi$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$er IV controller. (See Fig. 22 and 39.)
Differential Enthalphy Control
For differential enthalpy control, the EconoMi$er IV controller
uses two enthalpy sensors
CRENTDIF004A00), one in the outside air and one in the return
air duct. The EconoMi$er IV
air enthalpy to the return air enthalpy to determine EconoMi$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$er IV opens to
bring in outdoor air for free cooling.
Replace the standard outside air dry bulb temperature sensor with
the accessory enthalpy sensor in the same mounting location.
(See Fig. 22.) Mount the return air enthalpy sensor in the return
air duct. (See Fig. 37.) Wiring is provided in the EconoMi$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$er IV controller. When using this mode of
changeover control, turn the enthalpy setpoint potentiometer fully
clockwise to the D setting.
Indoor Air Quality (IAQ) Sensor Input
The IAQ input can be used for demand control ventilation control
based on the level of CO measured in the space or return air
2
duct.
Mount the accessory IAQ sensor according to manufacturer
specifications. The IAQ sensor should be wired to the AQ and
C06034
(HH57AC078 and
controller compares the outdoor
AQ1 terminals of the controller. Adjust the DCV potentiometers
to correspond to the DCV voltage output of the indoor air quality
sensor at the user-determined set point. (See Fig. 40.)
If a separate field-supplied transformer is used to power the IAQ
sensor, the sensor must not be grounded or the EconoMi$er IV
control board will be damaged.
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. 35.) 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. 35.) The minimum damper
position maintains the minimum airflow into the building during
the occupied period.
19
LED ON
18
D
17
LED ON
LED OFF
16
15
14
LED OFF
13
12
11
10
9
40 45 50 55 60
DEGREES FAHRENHEIT
Fig. 36 --- Outside Air Temperature
Changeover Set Points
ECONOMI$ER IV
Fig. 37 --- Return Air Temperature or Enthalpy
Sensor Mounting Location
31
C
LED ON
B
LED ON
LED OFF
A
LED OFF
100
65 70 75 80 85 90 95
C06035
ECONOMI$ER IV
CONTROLLER
GROMMET
RETURN AIR
SENSOR
RETURN DUCT
(FIELD-PROVIDED)
C06036