Carrier WeatherMaster Puron 48HC D17 Service And Maintenance Instructions page 51

ECONOMI$ER IV
Fig. 66 — Return-Air Temperature or Enthalpy
Sensor Mounting Location
OUTDOOR ENTHALPY CHANGEOVER
For enthalpy control, accessory enthalpy sensor (part number
HH57AC078) is required. Replace the standard outdoor dry
bulb temperature sensor with the accessory enthalpy sensor in
the same mounting location. (See Fig. 67.) When the outdoor
air enthalpy rises above the outdoor enthalpy changeover set-
point, the outdoor-air damper moves to its minimum position.
The outdoor enthalpy changeover setpoint is set with the out-
door enthalpy setpoint potentiometer on the EconoMi$er IV
controller. The setpoints are A, B, C, and D. (See Fig. 68.) The
factory-installed 620-ohm jumper must be in place across ter-
minals SR and SR+ on the EconoMi$er IV controller.
CONTROL
CONTROL POINT
CURVE APPROX. deg. F (deg. C)
AT 50% RH
A 73 (23)
B 70 (21)
C 67 (19)
D 63 (17)
65
(18)
60
(16)
A
55
(13)
B
50
C
(10)
45 D
(7)
40
(4)
35
(2)
35 40 45 50 55 60
(2) (4) (7) (10) (13) (16)
Fig. 67 — Enthalpy Changeover Setpoints
ECONOMI$ER IV
CONTROLLER
GROMMET
RETURN AIR
SENSOR
RETURN DUCT
85 90 95 100 105 110
(29) (32) (35) (38) (41) (43)
80
(27)
75
(24)
70
(21)
A
B
C
D
65 70 75 80 85 90 95 100 105 110
(18) (21) (24) (27) (29) (32) (35) (38) (41) (43)
N1
N
P1
P
T1
T
AQ1
AQ
SO+
SO
SR+
SR
Fig. 68 — 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 duct 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
outdoor) for cooling. For example, when the outdoor air has a
lower enthalpy than the return air, the EconoMi$er IV opens to
bring in outdoor air for free cooling.
Replace the standard outside air dry bulb temperature sensor
with the accessory enthalpy sensor in the same mounting loca-
tion. See Fig. 56. Mount the return air enthalpy sensor in the
return air duct. See Fig. 66. Wiring is provided in the
EconoMi$er IV wiring harness. See Fig. 59. The outdoor en-
thalpy changeover setpoint is set with the outdoor enthalpy set-
point potentiometer on the EconoMi$er IV controller. When
using this mode of changeover control, turn the enthalpy set-
point potentiometer fully clockwise to the D setting.
INDOOR AIR QUALITY (IAQ) SENSOR INPUT
The IAQ input can be used for demand controlled ventilation
control based on the level of CO
turn air duct.
Mount the accessory IAQ sensor according to manufacturer
specifications. The IAQ sensor should be wired to the AQ and
AQ1 terminals of the controller. Adjust the DCV potentiome-
ters to correspond to the DCV voltage output of the indoor air
quality sensor at the user-determined setpoint. See Fig. 69.
If a separate field-supplied transformer is used to power the
IAQ sensor, the sensor must not be grounded or the
EconoMi$er IV control board will be damaged.
HIGH LIMIT
When using demand ventilation, the minimum damper position
CURVE
represents the minimum ventilation position for VOC (volatile or-
ganic compounds) ventilation requirements. The maximum de-
mand ventilation position is used for fully occupied ventilation.
When demand ventilation control is not being used, the mini-
mum position potentiometer should be used to set the occupied
ventilation position. The maximum demand ventilation posi-
tion should be turned fully clockwise.
51
EXH
Set
2V 10V
EXH
Min
Pos
Open
DCV
Max
2V 10V
DCV
DCV
Set
2V 10V
Free
Cool
B C
D
A
measured in the space or re-
2
TR TR1
24
24 Vac
Vac
COM
HOT
_
+
1 2
5
4
3
EF1
EF