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