39
factory with a supply--air temperature sensor and an
outdoor-- air temperature sensor. This allows for operati on
of the EconoMi$er IV with outdoor air dry bulb
changeover control. Additional accessories can be added
to allow for different types of changeover control and
operation of the EconoMi$e r IV and unit.
Outdoor Dry Bulb Changeover
The standard control ler is shipped from the factory
configure d for outdoor dry bulb changeover control. The
outdoor air and supply air tempera ture sensors are
included as standard. For t his control mode, the outdoor
temperature is compared to a n a djustable setpoint selected
on the control. If the outdoor-air temperature is above the
setpoint, the EconoMi$er IV will adjust the outside air
dampers to minimum position. If the outdoor-air
temperature is below the setpoint, the position of the
outside air dampers will be controlled to provided free
cooling using outdoor air. When in this mode, the LED
next to the free c ooling setpoint potenti ometer will be on.
The changeover temperature setpoint is controlle d by the
free cool ing setpoint potentiometer locat ed on the control.
See Fig. 50. The scale on the potentiometer is A, B, C,
and D. See Fig. 71 for the corresponding temperat ure
change over value s.
C06034
Fig. 50 -- EconoMi$er IV Controlle r 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. 51 -- 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. 52 -- Outdoor--Air Damper Leakage
Differential Dry Bulb Control
For differential dry bulb control the standard outdoor dry
bulb sensor is used in conjunction with an additional
accessory dry bulb sensor (p/n: CRTEMPSN002A00). The
accessory sensor must be mounted in the return airstream.
See Fig. 53. 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. 53 -- 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 airs tr eam is us ed for cooling . When usin g this
mode of changeover control, turn the enthalpy setpoint
potentio meter fully clockwis e to the D settin g. See Fig . 50.
50HC
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