36
CONTROL
CURVE
A
B
C
D
CONTROL POINT
APPROX.
deg. F (deg. C)
AT 50% RH
73 (23)
70 (21)
67 (19)
63 (17)
1
2
1
4
1
6
1
8
2
0
2
2
2
4
26
28
30
32
3
4
3
6
3
8
40
42
4
4
46
9
0
1
0
0
80
70
6
0
50
4
0
30
20
1
0
ENTHALPY BTU PER POUND DRY AIR
85
(29)
90
(32)
95
(35)
100
(38)
105
(41)
110
(43)
35
(2)
35
(2)
40
(4)
40
(4)
105
(41)
110
(43)
45
(7)
45
(7)
50
(10)
50
(10)
55
(13)
55
(13)
60
(16)
60
(16)
65
(18)
65
(18)
70
(21)
70
(21)
75
(24)
75
(24)
80
(27)
80
(27)
85
(29)
90
(32)
95
(35)
100
(38)
A
A
B
B
C
C
D
D
RELATIVE HUMIDITY (%)
HIGH LIMIT
CURVE
APPROXIMATE DRY BULB TEMPERATURE--degrees F (degrees C)
C06037
Fig. 62 -- Enthalpy Changeover Setpoints
TR1
24 Vac
COM
TR
24
Vac
HOT
12
3
4
5
EF
EF1
+
_
P1
T1
P
T
N
EXH
2V 10V
EXH
Set
Set
2V 10V
2V 10V
DCV
DCV
Free
Cool
B
C
A
D
SO+
SR+
SR
SO
AQ1
AQ
DCV
Min
Pos
Open
Max
N1
C06038
Fig. 63 -- EonoMi $er IV Control
Differential E nthalpy C ontrol
For differential enthalpy control, the EconoMi$er IV
controller uses two enthalpy sensors (HH57AC078 and
CRENTDIF004A00), one in the outside air and one in the
return air duct. The EconoMi$er IV cont roller compares
the outdoor air enthalpy to the return air enthalpy to
determine EconoMi$er IV use. The controller selects the
lower enthalpy air (return or outdoor) for cool ing. For
exam ple, when the outdoor ai r has a lower enthalpy than
the return a ir, the EconoMi$er IV opens to bring in
outdoor air for free cooling.
Replace the standard outside air dry bulb temperature
sensor with the accessory enthalpy sensor in the same
mounting location. (See Fig. 52.) Mount the return air
enthalpy sensor in the return air duct. (See Fig. 61.)
Wiring is provided in the EconoMi$e r IV wiring harness.
(See Fig. 52.) The outdoor enthalpy changeover setpoint is
set with the outdoor enthalpy setpoint potentiometer on
the EconoMi$er IV controller. When using this mode of
change over control, turn t he e nthalpy setpoint
potentiometer fully clockwise to the D setting.
Indoor Air Quality (IAQ) Sensor Input
The IAQ input can be used for demand control ventilation
control based on the level of CO
2
measured in the space
or return air duct.
Mount the accessory IAQ sensor according to
manufacturer specifications. The IAQ sensor should be
wired to the AQ and AQ1 terminals of the controller.
Adjust the DCV potentiometers to correspond to the DCV
voltage output of the indoor air quality sensor at the
user-determined setpoint. (See Fig. 64.)
50TC
