22
Outdoor Enthalpy Changeover — For enthalpy control, ac-
cessory enthalpy sensor (part number HH57AC078) is re-
quired. Replace the standard outdoor dry bulb temperature
sensor with the accessory enthalpy sensor in the same mount-
ing location. See Fig. 24. 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$er IV controller. The
set points are A, B, C, and D. See Fig. 40. The factory-installed
620-ohm jumper must be in place across terminals SR and SR+
on the EconoMi$er IV controller. See Fig. 24 and 41.
Differential Enthalpy Control — For differential enthalpy
control, the EconoMi$er IV controller uses two enthalpy sen-
sors (HH57AC078 and CRENTDIF004A00), one in the out-
side air and one in the return air duct. The EconoMi$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. 24. Mount the return air enthalpy sensor in
the return air duct. See Fig. 39. Wiring is provided in the
EconoMi$er IV wiring harness. See Fig. 31. The outdoor en-
thalpy changeover set point is set with the outdoor enthalpy set
point potentiometer on the EconoMi$er IV controller. When
using this mode of changeover control, turn the enthalpy set-
point potentiometer fully clockwise to the D setting.
Indoor Air Quality (IAQ) Sensor Input — The IAQ input
can be used for demand control ventilation control based on the
level of CO
2
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. 42.
If a separate field-supplied transformer is used to power the
IAQ sensor, the sensor must not be grounded or the
EconoMi$er IV control board will be damaged.
Exhaust Set Point Adjustment — The exhaust set point will
determine when the exhaust fan runs based on damper position
(if accessory power exhaust is installed). The set point is modi-
fied with the Exhaust Fan Set Point (EXH SET) potentiometer.
See Fig. 37. The set point represents the damper position above
which the exhaust fans will be turned on. When there is a call
for exhaust, the EconoMi$er IV controller provides a 45 ± 15
second delay before exhaust fan activation to allow the damp-
ers to open. This delay allows the damper to reach the appro-
priate position to avoid unnecessary fan overload.
Minimum Position Control — There is a minimum damper
position potentiometer on the EconoMi$er IV controller. See
Fig. 37. The minimum damper position maintains the mini-
mum airflow into the building during the occupied period.
When using demand ventilation, the minimum damper po-
sition represents the minimum ventilation position for VOC
(volatile organic compound) ventilation requirements. The
maximum demand ventilation position is used for fully occu-
pied ventilation.
When demand ventilation control is not being used, the
minimum position potentiometer should be used to set the oc-
cupied ventilation position. The maximum demand ventilation
position should be turned fully clockwise.
Adjust the minimum position potentiometer to allow the
minimum amount of outdoor air, as required by local codes, to
enter the building. Make minimum position adjustments with
at least 10 F temperature difference between the outdoor and
return-air temperatures.
LED ON
LED ON
LED ON
LED ON
LED OFF
19
18
LED OFF
LED OFF
LED OFF
17
16
15
14
13
12
11
10
9
40
45
50
55
60
65
70
75
80
85
90
95
100
DEGREES FAHRENHEIT
mA
D
C
B
A
ECONOMI$ER IV
ECONOMI$ER IV
CONTROLLER
GROMMET
RETURN AIR
SENSOR
RETURN DUCT
(FIELD-PROVIDED)
Fig. 37 — EconoMi$er IV Controller Potentiometer
and LED Locations
Fig. 38 — Outdoor Air Temperature Changeover
Set Points
Fig. 39 — Return Air Temperature or
Enthalpy Sensor Mounting Location
