14
Installing Optional HH57AC081 Single Outside
Air Enthalpy Sensor
When using the HH57AC081 (Honeywell C7400S) enthalpy
sensor for outside air changeover (see Fig. 32), the existing
HH79ZZ007 dry bulb sensor must be removed. The enthalpy
sensor will be mounted in the same location as the dry bulb
sensor (see Fig. 1). When the enthalpy sensor’s OA tempera-
ture, enthalpy and dew point are below the respective set
points, the outside air can be used for free-cooling. When any
of these is above the set point, free-cooling will not be avail-
able. Figure 31 shows the enthalpy boundaries in the W7220
Jade controller. There are (5) enthalpy boundaries (set points
ES1 through ES5), which are defined by dry bulb temperature,
enthalpy, and dew point. ES3 is the default setting. Table 7
shows the High Limit Curves for each setting.
NOTE: To use the HH57AC081 sensor for outside air sensor, the
dipswitches on the sensor must be set to OFF-OFF-OFF. See
Table 8.
The (2) gray wires with a plug from the EconoMi$er X harness
in the return chamber plug directly into the HH57AC081 en-
thalpy sensor. See Fig. 25 and 30 for wiring.
Fig. 31 — Enthalpy Curve Boundaries
Fig. 32 — HH57AC081 Sensor, Dimensions and DIP
Switch Location
LEGEND
Table 7 — Single Enthalpy and Dual Enthalpy High Limit Curves
ENTHALPY
CURVE
TEMP.
DRY BULB (°F)
TEMP.
DEW POINT (°F)
ENTHALPY
(BTU/LB/DA)
POINT P1
POINT P2
TEMP (°F)
HUMIDITY %RH
TEMP (°F)
HUMIDITY %RH
ES1
80.0
60.0
28.0
80.0
36.8
66.3
80.1
ES2
75.0
57.0
26.0
75.0
39.6
63.3
80.0
ES3
70.0
54.0
24.0
70.0
42.3
59.7
81.4
ES4
65.0
51.0
22.0
65.0
44.8
55.7
84.2
ES5
60.0
48.0
20.0
60.0
46.9
51.3
88.5
HL
86.0
66.0
32.4
86.0
38.9
72.4
80.3
41/4 (108)
23/4 (70)
51/64 (21)
21/64 (55)
Table 8 — HH57AC081 Sensor DIP Switch
USE
DIP SWITCH POSITIONS FOR SWITCHES 1,2, & 3
1
2
3
DA
OFF
ON
OFF
RA
ON
OFF
OFF
OA
OFF
OFF
OFF
DA —
Discharge Air or Supply Sensor
RA —
Return Air
OA —
Outside Air
