Carrier 48FC M20 Series Service And Maintenance Instructions page 52

48FC-20-30 – Economizer Pressure Drop
0.12
0.10
0.08
0.06
0.04
0.02
0.00
3000 5000 7000
RETURN DUCT AIRFLOW (cfm)
Fig. 69 — Economizer Static Pressure Drop
EconoMi$er IV
Fig. 70 — Return Air Temperature or Enthalpy
Sensor Mounting Location
EXH
N1
Set
N
2V 10V
EXH
P1
P
Min
Pos
T1
Open
T
DCV
Max
2V 10V
AQ1
DCV
AQ
DCV
Set
SO+
2V 10V
SO
Free
SR+
Cool
B C
SR
D
A
Fig. 71 — EconoMi$er
9000 11000 13000 15000
EconoMi$er IV
Controller
Grommet
Return Air
Sensor
Return Duct
(Field-Provided)
TR TR1
24
24 Vac
Vac
COM
HOT
_
+
1 2
5
4
3
EF1
EF
® IV W7212 Control
CONTROL POINT
CONTROL
APPROX. °F (°C)
CURVE
AT 50% RH
A 73 (23)
B 70 (21)
C 67 (19)
D 63 (17)
55
(13)
50
C
(10)
D
45
(7)
40
(4)
35
(2)
35 40 45 50 55
(2) (4) (7) (10) (13)
APPROXIMATE DRY BULB TEMPERATURE °F (°C)
Fig. 72 — Enthalpy Changeover Set Points
Indoor Air Quality (IAQ) Sensor Input
The IAQ input can be used for demand controlled ventilation
control based on the level of CO
return air duct.
Mount the accessory IAQ sensor according to manufacturer
specifications. The IAQ sensor should be wired to the AQ and
AQ1 terminals of the controller. Adjust the DCV potentiome-
ters to correspond to the DCV voltage output of the indoor air
quality sensor at the user-determined set point. See Fig. 73.
If a separate field-supplied transformer is used to power the
IAQ sensor, the sensor must not be grounded or the
EconoMi$er ® IV control board will be damaged.
When using demand controlled ventilation, the minimum
damper position represents the minimum ventilation position
for VOC (volatile organic compounds) ventilation require-
ments. The maximum demand ventilation position is used for
fully occupied ventilation.
When demand controlled ventilation is not being used, the
minimum position potentiometer should be used to set the oc-
cupied ventilation position. The maximum demand ventilation
position should be turned fully clockwise.
CO Sensor Max Range Setting
6000
5000
4000
3000
2000
1000
0
2 3
Damper Voltage for Maximum Ventilation Rate
Fig. 73 — CO Sensor Maximum Range Settings
2
52
85 90 95 100 105
(29) (32) (35) (38) (41)
80
(27)
75
(24)
70
(21)
65
(18)
60
(16)
A
B
A
B
C
D
60 65 70 75 80 85 90 95 100 105
(16) (18) (21) (24) (27) (29) (32) (35) (38) (41)
measured in the space or
2
4 5 6 7 8
110
(43)
HIGH LIMIT
CURVE
110
(43)
800 ppm
900 ppm
1000 ppm
1100 ppm