Carrier 50HJ017 - Page 22

RETURN AIR
IAQ TEMPERATURE
SENSOR OR ENTHALPY
SENSOR
Fig. 34 -- Return Air Temperature or
Enthalpy Sensor Mounting Location
Outdoor Enthalpy Changeover -- For enthalpy control, ac-
cessory enthalpy sensor (p_ut number HH57AC078) is
required. Replace the standard outdoor dry bulb temperature
sensor with the accessory enthalpy sensor in the same mount-
ing location. See Fig. 27. When the outdoor air enthalpy rises
above file outdoor enthalpy changeover set point, file outdoor-
air damper moves to its minimum position. The outdoor
enthalpy changeover set point is set with the outdoor enth_dpy
set point potentiometer on the EconoMiSerlV controllel: The
set points are A, B, C, and I). See Fig. 35. The factory-installed
620-chin jumper must be in place across terminals SR and SR+
on the EconoMiSerIV controllel: See Fig. 30 and 36.
Differential Enthalpy Control -- For differential enth_dpy
control, the EconoMiSerIV controller uses two enthalpy sen-
sors (HH57AC078 and CRENTI)IF004A00), one in the out-
side air and one in the return airstream or the EconoMiSerIV
frame. The EconoMiSerlV controller compmes the outdoor air
enthalpy to file return air enthalpy to determine EconoMi$erIV
use. The controller selects the lower enthalpy air (return or out-
door) for cooling. For example, when the outdoor air has a low-
er enth_dpy than the return air and is below the set point, the
EconoMiSerIV opens to bring in outdoor tfir for free cooling.
Replace the standard outside air dry bulb temperature sen-
sor with the accessory entbalpy sensor in the same mounting
location. See Fig. 27. Mount the return air enthalpy sensor in
the return airstream. See Fig. 34. The outdoor enthalpy
changeover set point is set with the outdoor enthalpy set point
potentiometer on the EconoMiSerlV controller. When using
this mode of changeover control, turn the enthalpy setpoint po-
tentiometer fully clockwise to the D setting.
CONTROL CONTROL POINT
CURVE APPROX. °F (°C)
AT 50% RH
A 73123)
B 70(21)
C 67 {19)
D 63 (17)
85 90 95 100 105 110
(29) (32) (35) (38) (41) (43)
7-,
-.,/
7,,
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-../
y.,.
\
-./
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)<
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HIGH LIMIT
CURVE
35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110
(2) (4) (7) (10) (13) (16) (18) (21) (24) (27) (29) (32) (35) (38) (41) (43)
APPROXIMATE DRY BULB TEMPERATURE-- °F (°C)
Fig. 35 -- Enthalpy Changeover Set Points
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