
37
Fig. 70 — Outside Air Temperature Changeover
Set Points
Fig. 71 — 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. 72. Wiring is
provided in the EconoMi$er IV wiring harness.
In this mode of operation, the outdoor-air temperature is com-
pared to the return-air temperature and the lower temperature
airstream is used for cooling. When using this mode of change-
over control, turn the enthalpy set point potentiometer fully
clockwise to the D setting. See Fig. 69.
OUTDOOR ENTHALPY CHANGEOVER
For enthalpy control, accessory enthalpy sensor (P/N:
HH57AC078) is required. Replace the standard outdoor dry
bulb temperature sensor with the accessory enthalpy sensor in
the same mounting location. See Fig. 73. When the outdoor air
enthalpy rises above the outdoor enthalpy changeover set
point, the outdoor-air damper moves to its minimum position.
The outdoor enthalpy changeover set point is set with the out-
door enthalpy set point potentiometer on the EconoMi$er IV
controller. The set points are A, B, C, and D. See Fig. 74. The
factory-installed 620-ohm jumper must be in place across ter-
minals S
R
and SR+ on the EconoMi$er IV controller.
Fig. 72 — Return Air Temperature or Enthalpy Sensor
Mounting Location
Fig. 73 — EconoMi$er IV Control
DIFFERENTIAL ENTHALPY CONTROL
For differential enthalpy control, the EconoMi$er IV controller
uses two enthalpy sensors (HH57AC078 and CRENT-
DIF004A00), one in the outside air and one in the return air
duct. The EconoMi$er IV controller compares the outdoor air
enthalpy to the return air enthalpy to determine EconoMi$er IV
use. The controller selects the lower enthalpy air (return or out-
door) for cooling. For example, when the outdoor air has a
lower enthalpy than the return air, the EconoMi$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 loca-
tion. See Fig. 73. Mount the return air enthalpy sensor in the
return air duct. See Fig. 72. Wiring is provided in the
EconoMi$er IV wiring harness. See Fig. 65. The outdoor en-
thalpy changeover set point is set with the outdoor enthalpy set
point potentiometer on the EconoMi$er IV controller. When
using this mode of changeover control, turn the enthalpy set
point potentiometer fully clockwise to the D setting.
LED ON
LED ON
LED ON
LED ON
LED OFF
19
1
8
LED OFF
LED OFF
LED OFF
17
16
15
14
1
3
12
11
10
9
40
45
50
55
60
65
70
75
8
0
8
5
90
95
100
DEGREE
S
FAHRENHEIT
mA
D
C
B
A
0
5
10
15
20
25
3
0
0.1
3
0.20
0.22
0.25
0.
3
0
0.
3
5
0.40
0.45
0.50
S
TATIC PRE
SS
URE (in. wg)
FLOW
IN
CUBIC
FEET
PER
MINUTE
(cfm)
ECONOMI$ER IV
ECONOMI$ER IV
CONTROLLER
GROMMET
RETURN AIR
S
EN
S
OR
RETURN DUCT
(FIELD-PROVIDED)
TR1
24 V
a
c
COM
TR
24
V
a
c
HOT
1
2
3
4
5
EF
EF1
+
_
P1
T1
P
T
N
EXH
2V
10V
EXH
S
et
S
et
2V
10V
2V
10V
DCV
DCV
Free
Cool
B
C
A
D
S
O+
S
R+
S
R
S
O
AQ1
AQ
DCV
Min
Po
s
Open
M
a
x
N1
Summary of Contents for WeatherMaster 50HC04
Page 32: ...32 Fig 63 RTU Open Overlay for Economizer Wiring ...
Page 33: ...33 Fig 64 VFD Overlay for W2770 Controller Wiring ...
Page 86: ...86 Fig C 50HC A07 PAC Control Diagram 208 230 3 60 460 575 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 91: ...91 Fig H 50HC D12 PAC Control Diagram 208 230 3 60 460 575 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 93: ...93 Fig J 50HC A04 A06 PAC Power Diagram 208 230 1 60 APPENDIX D WIRING DIAGRAMS ...
Page 95: ...95 Fig L 50HC A07 PAC Power Diagram 208 230 3 60 460 3 60 575 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 100: ...100 Fig Q 50HC D11 PAC Power Diagram 208 230 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 101: ...101 Fig R 50HC D11 PAC Power Diagram 460 3 60 575 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 103: ...103 Fig T 50HC D14 PAC Power Diagram 208 230 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 104: ...104 Fig U 50HC D14 PAC Power Diagram 460 3 60 575 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 124: ...124 Fig AO PremierLink System A04 A06 Wiring Diagram APPENDIX D WIRING DIAGRAMS ...
Page 125: ...125 Fig AP RTU Open System Control A04 A06 Wiring Diagram APPENDIX D WIRING DIAGRAMS ...
Page 126: ...126 Fig AQ PremierLink System A07 D14 Wiring Diagram APPENDIX D WIRING DIAGRAMS ...
Page 127: ...127 Fig AR RTU Open A07 D14 Wiring Diagram APPENDIX D WIRING DIAGRAMS ...