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temperature is compared to an adjustable setpoint selected
on the control. If the outdoor-air temperature is above the
setpoint, the EconoMi$er IV will adjust the outside air
dampers to minimum position. If the outdoor-air
temperature is below the setpoint, the position of the
outside air dampers will be controlled to provided free
cooling using outdoor air. When in this mode, the LED
next to the free cooling setpoint potentiometer will be on.
The changeover temperature setpoint is controlled by the
free cooling setpoint potentiometer located on the control.
See Fig. 87. The scale on the potentiometer is A, B, C,
and D. See Fig. 88 for the corresponding temperature
changeover values.
Fig. 87 - - EconoMi$er IV Controller Potentiometer and LED
Locations
19
LED ON
18
D
17
LED ON
16
LED OFF
C
15
14
LED OFF
13
12
11
10
9
40
45
50
55
60
65
DEGREES FAHRENHEIT
Fig. 88 - - Outside Air Temperature Changeover Setpoints
30
25
20
15
10
5
0
0.13
0.20 0.22
0.25
STATIC PRESSURE (in. wg)
Fig. 89 - - Outdoor- -Air Damper Leakage
C06034
LED ON
B
LED ON
LED OFF
A
LED OFF
100
70
75
80
85
90
95
C06035
0.30 0.35 0.40
0.45
0.50
C06031
Differential Dry Bulb Control
For differential dry bulb control the standard outdoor dry
bulb sensor is used in conjunction with an additional
accessory
dry
bulb
CRTEMPSN002A00). The accessory sensor must be
mounted in the return airstream. See Fig. 90. Wiring is
provided in the EconoMi$er IV wiring harness.
See Fig. 83.
ECONOMI$ERIV
Fig. 90 - - Return Air Temperature or Enthalpy Sensor Mount-
ing Location
In this mode of operation, the outdoor-air temperature is
compared to the return-air temperature and the lower
temperature 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.
87.
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.
90. When the outdoor air enthalpy rises above the outdoor
enthalpy changeover setpoint, the outdoor-air damper
moves to its minimum position. The outdoor enthalpy
changeover setpoint is set with the outdoor enthalpy
setpoint potentiometer on the EconoMi$er IV controller.
The setpoints are A, B, C, and D. See Fig.91. The
factory-installed 620-ohm jumper must be in place across
terminals S
and SR+ on the EconoMi$er IV controller.
R
81
sensor
(part
number
ECONOMI$ERIV
CONTROLLER
GROMMET
RETURN AIR
SENSOR
RETURN DUCT
(FIELD-PROVIDED)
C070FIG
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