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Table 10 — Supply Air Sensor Temperature/
Resistance Values
C. EconoMi$erIV Control Modes
Determine the EconoMi$erIV control mode before set up of the
control. Some modes of operation may require different sensors.
Refer to Table 11. The EconoMi$erIV is supplied from the fac-
tory with a supply air temperature sensor, a low temperature
compressor lockout switch, and an outdoor air temperature
sensor. This allows for operation of the EconoMi$erIV with out-
door air dry bulb changeover control. Additional accessories
can be added to allow for different types of changeover control
and operation of the EconoMi$erIV and unit.
Outdoor Dry Bulb Changeover
The standard controller is shipped from the factory config-
ured for outdoor dry bulb changeover control. The outdoor
air and supply air temperature sensors are included as stan-
dard. For this control mode, the outdoor temperature is com-
pared to an adjustable set point selected on the control. If the
outdoor-air temperature is above the set point, the
EconoMi$erIV will adjust the outdoor-air dampers to mini-
mum position. If the outdoor-air temperature is below the set
point, the position of the outdoor-air dampers will be con-
trolled to provide free cooling using outdoor air. When in this
mode, the LED next to the free cooling set point potentiome-
ter will be on. The changeover temperature set point is con-
trolled by the free cooling set point potentiometer located on
the control. See Fig. 28. The scale on the potentiometer is A,
B, C, and D. See Fig. 29 for the corresponding temperature
changeover 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
LEGEND
DCV — Demand Controlled Ventilation
IAQ — Indoor Air Quality
LALS— Low Temperature Compressor
Lockout Switch
OAT — Outdoor-Air Temperature
POT — Potentiometer
Potentiometer Default Settings:
Power Exhaust Middle
Minimum Pos. Fully Closed
DCV Max. Middle
DCV Set Middle
Enthalpy C Setting
NOTES:
1. 620 ohm, 1 watt 5% resistor should be removed only when using differential
enthalpy or dry bulb.
2. If a separate field-supplied 24 v transformer is used for the IAQ sensor power
supply, it cannot have the secondary of the transformer grounded.
3. For field-installed remote minimum position POT, remove black wire jumper
between P and P1 and set control minimum position POT to the minimum
position.
Fig. 27 — EconoMi$erIV Wiring