13
Since 1965
MicroMetl
Economizing
Figure 29 – Enthalpy Curve Boundaries
9901-2022 SINGLE OUTSIDE AIR ENTHALPY
SENSOR
When using the 9901-2022 (Honeywell C7400S) enthalpy sensor
(See Figure 30) for outside air changeover, the existing 9901-2021
(Honeywell C7250) dry bulb sensor must be removed if applicable.
See Figure 1. When the enthalpy sensor’s OA temperature,
enthalpy and dew point are below the respective setpoints, the
outside air can be used for free-cooling. When any of these is
above the setpoint, free-cooling will not be available. Figure 29
shows the enthalpy boundaries in the W7220 Jade controller.
There are (5) enthalpy boundaries (setpoints ES1 thru 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.
Important: to use the 9901-2022 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 economizer harness in the
return chamber plug directly into the 9901-2022 enthalpy sensor.
See Figures 23 and 28 for wiring.
Table 7 – Single Enthalpy and Dual Enthalpy High Limit Curves
ENTHALPY
CURVE
TEMP. DRY
BULB (F)
TEMP.
DEWPOINT (F)
ENTHALPY
(btu/lb/da)
POINT P1
POINT P2
TEMP. (F)
HUMIDITY
(%RH)
TEMP. (F)
HUMIDITY
(%RH)
ES1
80
60
28.0
80
36.8
66.3
80.1
ES2
75
57
26.0
75
39.6
63.3
80.0
ES3
70
54
34.0
70
42.3
59.7
81.4
ES4
65
51
22.0
65
44.8
55.7
84.2
ES5
60
48
20.0
60
46.9
51.3
88.5
HL
86
66
32.4
86
38.9
72.4
80.3
Figure 30 - 9901-2022 (C7400S) Dimensional,
connection and switching information
Table 8 – 9901-2022 Sensor Dip Switch Settings
USE
DIP SWITCH POSITIONS FOR SWITCHES 1, 2, AND 3
1
2
3
DA
OFF
ON
OFF
RA
ON
OFF
OFF
OA
OFF
OFF
OFF
DA -
Discharge Air (not used on economizer)
RA -
Return Air
OA -
Outside Air
Default Setting = OFF-OFF-OFF
D
A
R
A
O
A
1
2
3
S-Bu
s
Temp & Humidity
9901-2022
4-1/4
2-3/4
2-1/64
S-B
u
s
