38
Fig. 58 — Supply Air Sensor Location
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.
Outdoor Air Lockout Sensor
The EconoMi$er IV is equipped with an ambient temperature
lockout switch located in the outdoor airstream which is used
to lock out the compressors below a 42°F (6°C) ambient tem-
perature. (See Fig. 51.)
ECONOMI$ER IV CONTROL MODES
Determine the EconoMi$er IV control mode before set up of
the control. Some modes of operation may require different
sensors. The EconoMi$er IV is supplied from the factory with
a supply-air temperature sensor and an outdoor-air temperature
sensor. This allows for operation of the EconoMi$er IV with
outdoor air dry bulb changeover control. Additional accesso-
ries can be added to allow for different types of changeover
control and operation of the EconoMi$er IV and unit.
Outdoor Dry Bulb Changeover
The standard controller is shipped from the factory configured
for outdoor dry bulb changeover control. The outdoor air and
supply air temperature sensors are included as standard. For
this control mode, the outdoor temperature is compared to an
adjustable set point selected on the control. If the outdoor-air
temperature is above the set point, the EconoMi$er IV will ad-
just the outside air dampers to minimum position. If the out-
door-air temperature is below the set point, the position of the
outside air dampers will be controlled to provided free cooling
using outdoor air. When in this mode, the LED next to the free
cooling set point potentiometer will be on. The changeover
temperature set point is controlled by the free cooling set point
potentiometer located on the control. (See Fig. 59.) The scale
on the potentiometer is A, B, C, and D. See Fig. 60 for the cor-
responding temperature changeover values.
Fig. 59 — EconoMi$er IV Controller Potentiometer
and LED Locations
Table 14 — Thermistor Resistance vs Temperature
Values for Space Temperature Sensor, Supply Air
Temperature Sensor, and Outdoor Air
Temperature Sensor
TEMP (°C) TEMP (°F)
RESISTANCE
(ohms)
-40 -40 335,651
-35 -31 242,195
-30 -22 176,683
-25 -13 130,243
-20 -4 96,974
-15 5 72,895
-10 14 55,298
-5 23 42,315
0 32 32,651
5 41 25,395
10 50 19,903
15 59 15,714
20 68 12,494
25 77 10,000
30 86 8,056
35 95 6,530
40 104 5,325
45 113 4,367
50 122 3,601
55 131 2,985
60 140 2,487
65 149 2,082
70 158 1,752
SUPPLY
AIR TEMPERATURE
SENSOR MOUNTING
LOCATION
SUPPLY AIR
TEMPERATURE
SENSOR
(SEALED
INSIDE CRIMP
END)
IMPORTANT: The optional EconoMi$er2 does not include
a controller. The EconoMi$er2 is operated by a 4 to 20 mA
signal from an existing field-supplied controller. See
Fig. 52 for wiring information.
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