Carrier 50TFQ008-012 - Manual (Page 21)

21
ECONOMI$ER IV STANDARD SENSORS
Outdoor Air Temperature (OAT) Sensor — The outdoor air
temperature sensor (HH57AC074) is a 10 to 20 mA device
used to measure the outdoor-air temperature. The outdoor-air
temperature is used to determine when the EconoMi$er IV can
be used for free cooling. The sensor is factory-installed on the
EconoMi$er IV in the outdoor airstream. See Fig. 19. The op-
erating range of temperature measurement is 40 to 100 F.
Supply Air Temperature (SAT) Sensor — The supply air
temperature sensor is a 3 K thermistor located at the inlet of the
indoor fan. See Fig. 31. This sensor is factory installed. The op-
erating range of temperature measurement is 0° to 158 F. See
Table 6 for sensor temperature/resistance values.
The temperature sensor looks like an eyelet terminal with
wires running to it. The sensor is located in the “crimp end”
and is sealed from moisture.
Table 6 — Supply Air Sensor Temperature/
Resistance Values
Outdoor Air Lockout Sensor — The Economi$er IV is
equipped with an ambient temperature lockout switch located
in the outdoor air stream which is used to lockout the compres-
sors below a 42 F ambient temperature. See Fig. 19.
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 sen-
sors. Refer to Table 7. 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 accessories can be added to allow for different types
of changeover control and operation of the EconoMi$er IV and
unit.
Table 7 — EconoMi$er IV Sensor Usage
*CRENTDIF004A00 and CRTEMPSN002A00 accessories are
used on many different base units. As such, these kits may con-
tain parts that will not be needed for installation.
†33ZCSENCO2 is an accessory CO
2
sensor.
**33ZCASPCO2 is an accessory aspirator box required for duct-
mounted applications.
††CRCBDIOX005A00 is an accessory that contains both
33ZCSENCO2 and 33ZCASPCO2 accessories.
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$er IV will adjust the outdoor air
dampers to minimum position. If the outdoor-air temperature is
below the set point, the position of the outdoor air dampers will
be controlled to provide free cooling using outdoor air. When
in this mode, the LED next to the free cooling set point potenti-
ometer will be on. The changeover temperature set point is
controlled by the free cooling set point potentiometer located
on the control. See Fig. 32. The scale on the potentiometer is A,
B, C, and D. See Fig. 33 for the corresponding temperature
changeover values.
TEMPERATURE (F) RESISTANCE (ohms)
–58 200,250
–40 100,680
–22 53,010
–4 29,091
14 16,590
32 9,795
50 5,970
68 3,747
77 3,000
86 2,416
104 1,597
122 1,080
140 746
158 525
176 376
185 321
194 274
212 203
230 153
248 116
257 102
266 89
284 70
302 55
IMPORTANT: The optional EconoMi$er2 does not
include a controller. The EconoMi$er2 is operated by a 4 to
20 mA signal from an existing field-supplied controller
(such as PremierLink™ control). See Fig. 27 for wiring
information.
APPLICATION
ECONOMI$ER IV WITH OUTDOOR AIR
DRY BULB SENSOR
Accessories Required
Outdoor Air
Dry Bulb
None. The outdoor air dry bulb sensor
is factory installed.
Differential
Dry Bulb
CRTEMPSN002A00*
Single Enthalpy HH57AC078
Differential
Enthalpy
HH57AC078
and
CRENTDIF004A00*
CO
2
for DCV
Control using a
Wall-Mounted
CO
2
Sensor
33ZCSENCO2
CO
2
for DCV
Control using a
Duct-Mounted
CO
2
Sensor
33ZCSENCO2†
and
33ZCASPCO2**
OR
CRCBDIOX005A00††
SUPPLY AIR
TEMPERATURE
SENSOR
MOUNTING
LOCATION
SUPPLY AIR
TEMPERATURE
SENSOR
Fig. 31 — Supply Air Sensor Location