14
Since 1965
MicroMetl
INSTALLING DIFFERENTIAL RETURN AIR
SENSOR
The 9901-2022-DIFF JC2 dierential return sensor kit must be
eld mounted in the system’s return duct work. The kit includes a
wiring harness, that connects the economizer harness in the return
chamber of the unit, to the provided 9901-2022 sensor. Wire per
Figure 31.
In addition to using the 9901-2022 (Honeywell C7400S) sensor
(See Figure 30) for a single enthalpy sensor, it can also be used as
a dierential return enthalpy or dry bulb sensor. Figure 29 shows
the dual enthalpy boundaries in the W7220 Jade controller. With
dual enthalpy The HIGH LIMIT boundary is ES1 when there are no
stages of mechanical cooling energized and HL (high limit) when
a compressor stage is energized. Table 7 shows the High Limit
Curves for each setting. Important: to use the 9901-2022 sensor for
dierential return air, the dipswitches on the sensor must be set to
ON-OFF-OFF. See Table 8.
When using the 9901-2022-DIFF JC2 dierential return enthalpy
or dry bulb temperature option, see Table 9 for California Title 24
setting requirements by region.
Figure 31 – Wiring Dierential Return Air Sensor
CALIFORNIA’S TITLE 24 HIGH TEMPERATURE
LIMIT SETTINGS
California’s Title 24 code requires a high temperature limit
setting for all dry bulb outside air economizer change over. The
temperatures vary by the region within California. See Table 9 for
high limit settings.
Table 9 – California Title 24 Regional High Limit
Dry Bulb Temperature Settings
12-Pin Female
Plug from Economizer
BLU
BLK
GRA GRA GRA
GRA GRA
GRA
GRA
PNK
VIO
6
7
2
3
10
11
5
1
12
9
4
8
RED
ORG
PL6
Plug
12-Pin Male
Plug in Unit
BRN
YEL
*9901-2022
Differential Return
Sensor. Field Mounted
in Return Duct
Wiring
Harness*
*Provided in
9901-2022-DIFF JC2 Kit
DEVICE TYPE*
CLIMATE
ZONES
REQUIRED HIGH LIMIT
(ECONOMIZER OFF
WHEN):
DESCRIPTION
FIXED DRY BULB
1, 3, 5, 11-16 OAT exceeds 75°F
2, 4, 10 OAT exceeds 73°F
6, 8, 9 OAT exceeds 71°F
7 OAT exceeds 69°F
DIFFERENTIAL
DRY BULB
1, 3, 5, 11-16 OAT exceeds RA Temp.
2, 4, 10 OAT exceeds -2°F
6, 8, 9 OAT exceeds -4°F
7 OAT exceeds -4°F
FIXED ENTHALPY†
+ FIXED DRY BULB
ALL
OAT exceeds 28 Btu/lb of
dry air or OAT exceeds 75°F
* Only the high limit control devices listed are allowed to be used and at the setpoints listed. Others
such as Dew Point, Fixed Enthalpy, Electronic Enthalpy, and Dierential Enthalpy Controls, may
not be used in any climate zone for compliance with Section 140.4(e)1 unless approval for use is
provided by the Energy Commission Executive Director.
† At altitudes substantially dierent than sea level, the Fixed Enthalpy limit value shall be set to
the enthalpy value at 75°F and 50% relative humidity. As an example, at approximately 6,000 foot
elevation, the xed enthalpy limit is approximately 30.7 Btu/lb.
DEMAND CONTROL VENTILATION
Refer to economizer wiring diagram Figures 23 and 28 and DCV
instructions if demand control ventilation (CO2 sensor) is used.
CO2 sensor will wire into the blue and black connections at the
Jade controller as shown in Figures 23, 28 and 32. If a eld installed
CO2 sensor is connected to the economizer controller, a demand
controlled ventilation strategy will operate automatically. As the CO2
level in the space increases above the setpoint (on the economizer
controller), the minimum position of the dampers will be increased
proportionally, until the Maximum Ventilation setting is reached. As
the space CO2 level decreases because of the increase in fresh
air, the outdoor damper will follow the higher demand condition
from the DCV mode or from the free cooling mode.
Figure 32 – CO2 wiring connections to Jade
controller
Black Wire
IAQ 2-10 Vdc
Blue Wire
IAQ COM
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