Carrier 48HC*04–14 - Outdoor Dry Bulb Changeover; Differential Dry Bulb Control

55
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.
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 compare d to an adjustable setpoint selected
on the control. If the outdoor-air tempe rature is above the
setpoint, the EconoMi$er IV will adj ust the outside air
dampers to minimum position. If the outdoor-air
temperature is below the setpoint, the position of the
outside air dampers will be controlled to provided free
cooling using outdoor air. W hen in this mode, the LED
next to the free c ooling setpoint potentiometer wil l be on.
The changeover temperature setpoint i s c ontrolled by the
free cooling setpoint potentiometer located on the control.
See Fig. 68. The scale on the potentiometer is A, B, C,
and D. See Fig. 71 for the corresponding temperature
change over value s.
C06034
Fig. 68 -- EconoMi$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. 69 -- 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. 70 -- Outdoor--Air Damper Leakage
Differential Dry Bulb Control
For differential dry bulb control the standard outdoor dry
bulb sensor is used i n conjunction with a n additional
accessory dry bulb sensor (p/n: CRTEMPSN002A00). The
accessory sensor must be mounted in the return airstream.
See Fig. 71. Wiring is provided in the EconoMi$er IV
wiring harness.
ECONOMI$ERIV
ECONOMI$ERIV
CONTROLLER
GROMMET
RETURN AIR
SENSOR
RETURN DUCT
(FIELD-PROVIDED)
C07085
Fig. 71 -- Return Air Temperature or Enthalpy Sensor
Mounting Location
In this mode of operation, the outdoor-air temperature is
compared to the return-air temperature and the lower
temperatur e airstream is used for cooling . When using this
mode of changeover control, turn the enthalpy setpoint
potentio meter fully clockw is e to the D setting. See Fig. 68.
48HC