Carrier 48TC*D08 - EconoMi$er IV Control Modes; Outdoor Dry Bulb Changeover

60
Supply Air Temperature (SAT) Sensor
The supply air temperature sensor is a 3 K t hermistor
located at the inlet of the indoor fan. (See Fig. 76.) This
sensor is factory installed. The operating range of
temperature measurement is 0 to 158_F(--18_ to 70_C).
See Table 15 for sensor temperature/resistance values.
SUPPLY AIR
TEMPERATURE
SENSOR
MOUNTING
LOCATION
SUPPLY AIR
TEMPERATURE
SENSOR
C06033
Fig. 76 -- Supply Air Sensor Location
The temperature sensor looks like an eyelet terminal with
wires running to i t. The sensor is located in t he “crimp
end” and is sealed from moisture.
Outdoor Air Lockout Sensor
The E conoMi$er IV is equipped with an ambient
temperature lockout switch located in the outdoor
airstream which is used to lock out the compressors below
a42_F(6_C) ambient temperature. (See Fig. 71.)
EconoMi$e r IV Control
Modes
IMPORTANT: The optional EconoMi$e r 2 does not
include a controller. The EconoMi$er2 i s operated by a 4
to 20 mA signal from an existing field-supplied controller
(such as PremierLink control). See Fig. 74 for wiring
information.
Determine the EconoMi$er IV control mode before set up
of the control. Some modes of operation may require
different sensors. (See Table 27.) The EconoMi$er IV is
supplied from the factory with a supply-air temperature
sensor and an out door-air temperature sensor. This allows
for operation of the EconoMi$er IV with outdoor air dry
bulb changeover control. Additional accessories can be
added to allow for different types of changeover control
and opera tion of the EconoMi$e r IV and unit.
Outdoor Dry Bulb Changeover
The standard controller is shipped from the factory
configure d 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 setpoint selected
on the cont rol. If the outdoor-air temperature is above the
setpoint, the EconoMi$er IV wil l adjust the outside air
dampers to minimum position. If the outdoor-air
temperature is below the setpoint, the position of the
outside air dampers will be controlled to provided free
cooling using outdoor air. When in this mode, the LED
next to the free cooling setpoint potentiometer will be on.
The changeove r temperature setpoint is controlled by the
free c ooling setpoint potentiometer located on the cont rol.
(See Fig. 77.)
The scale on the potentiometer is A, B, C, and D. See Fig.
74 for the c orresponding temperature changeover values.
C06034
Fig. 77 -- EconoMi$er IV Controller Potentiometer
and LED Locations
LED ON
LED ON
LED ON
LED ON
LED OFF
19
18
LED OFF
LED OFF
LED OFF
17
16
15
14
13
12
11
10
9
40
45
50
55
60
65
70
75
80
85
90
95
100
DEGREES FAHRENHEIT
mA
D
C
B
A
C06035
Fig. 78 -- Outside Air Temperature Changeover
Setpoints
0
5
10
15
20
25
30
0.13 0.20 0.22 0.25 0.30 0.35 0.40 0.45 0.50
STATIC PRESSURE (in. wg)
FLOW IN CUBIC FEET PER MINUTE (cfm)
C06031
Fig. 79 -- Outdoor--Air Damper Leakage
48TC