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CONFIGURATION
EconoMi$er IV Standard Sensors
OUTDOOR AIR TEMPERATURE (OAT) SENSOR
The outdoor air temperature sensor is a 10 to 20 mA device used
to measure the outdoor-air temperature. The outdoor-air
temperature is used to determine when the EconoMi$er IV system
can be used for free cooling. The sensor is factory-installed on the
EconoMi$er IV in the outdoor airstream. (See Fig. 38.) The sensor
has 8 selectable temperature changeover set points, ranging from
48°F (9°C) to 78°F (25°C). The temperature changeover is set
using the 3 dip switches on the sensor. The ABCD potentiometer
on the controller should be set to the "D" position.
SUPPLY AIR TEMPERATURE (SAT) SENSOR
The supply air temperature sensor is a 3K thermistor located at the
inlet of the indoor fan. (See Fig. 38.) This sensor is field installed.
The operating range of temperature measurement is 0°F (-18°C) to
158°F (70°C). See Table 4 for sensor temperature/resistance
values.
The temperature sensor looks like an eyelet terminal with wires
running to it. The sensor is located in the "crimp end" and is sealed
from moisture.
LOW
TEMPERATURE
SWITCH
The EconoMi$er IV assembly is equipped with a low ambient
temperature lockout switch located in the outdoor airstream which
is used to lock out the compressors below a 42°F (6°C) ambient
temperature. (See Fig. 38.)
COMPRESSOR
LOCKOUT
Outside Air
Damper
Fig. 38 — EconoMi$er IV Component Locations
Table 4 — Supply Air Sensor Temperature/
TEMPERATURE (°F)
Economizer
Actuator
16
Resistance Values
RESISTANCE (ohms)
–58
–40
–22
–4
14
32
50
68
77
86
104
122
140
158
176
185
194
212
230
248
257
266
284
302
Low Temp.
Lockout
Wiring
Harness
EconoMi$er IV
Controller
Outside Air
Temp (OAT)
Sensor
Return Air Damper
200,250
100,680
53,010
29,091
16,590
9,795
5,970
3,747
3,000
2,416
1,597
1,080
746
525
376
321
274
203
153
116
102
89
70
55
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