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Installing Differential Return Air Sensor
The CRDIFRASN01A00 differential return sensor kit must be
field mounted in the system's return duct work. The kit includes a
wiring harness that connects the EconoMi$er X harness in the
return chamber of the unit to the provided HH57AC081 sensor.
Wire according to Fig. 37.
In addition to using the HH57AC081 (Honeywell C7400S) sen-
sor (see Fig. 32) for a single enthalpy sensor, it can also be used as
a differential return enthalpy or dry bulb sensor. Figure 31 shows
the dual enthalpy boundaries in the W7220 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.
NOTE: To use the HH57AC081 sensor for differential return air,
the DIP switches on the sensor must be set to ON-OFF-OFF. (See
Table 8.)
When using the CRDIFRASN01A00 differential return enthalpy
or dry bulb temperature option, see Table 9 for California Title 24
setting requirements by region.
12-Pin Female Plug
From Economizer
VIO
6
PNK
7
BLU
2
BLK
3
GRA
10
GRA
11
5
RED
1
12
ORG
9
BRN
4
YEL
8
PL6
PLUG
12-Pin Male
Plug In Unit
*HH57AC081
Differential return
sensor field mounted
in return duct.
*Provided in CRDIFRAS001A00 Kit
Fig. 37 — Wiring Differential 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.
GRA
GRA
GRA
Wiring
Harness*
Table 9 — California Title 24 Regional High Limit Dry
Bulb Temperature Settings
TABLE 140.4-B AIR ECONOMIZER HIGH LIMIT SHUT OFF
CONTROL REQUIREMENTS
CLIMATE
DEVICE TYPE*
ZONES
1, 3, 5, 11-16
2, 4, 10
FIXED DRY
BULB
6, 8, 9
7
1, 3, 5, 11-16
2, 4, 10
DIFFERENTIAL
DRY BULB
6, 8, 9
7
FIXED
ENTHALPY†
All
+ FIXED DRY
BULB
* Only the high limit control devices listed are allowed to be used and at the set
points listed. Others such as Dew Point, Fixed Enthalpy, Electronic Enthalpy, and
Differential 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 different 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 fixed enthalpy limit is
approximately 30.7 Btu/lb.
Demand Controlled Ventilation
Refer to EconoMi$er X wiring diagram (Fig. 25 and 36) and DCV
instructions if demand controlled ventilation (CO
The CO
sensor will wire into the blue and black connections at
2
the controller as shown in Fig. 25, 36, and 38. If a field-installed
CO
sensor is connected to the EconoMi$er X controller, a
2
demand controlled ventilation strategy will operate automatically.
As the CO
level in the space increases above the setpoint (on the
2
EconoMi$er X controller), the minimum position of the dampers
will be increased proportionally, until the Maximum Ventilation
setting is reached. As the space CO
increase in fresh air, the outdoor damper will follow the higher
demand condition from the DCV mode or from the free cooling
mode.
Blue Wire
IAQ COM
Fig. 38 — CO
Wiring Connections to Controller
2
16
REQUIRED HIGH LIMIT
(ECONOMIZER
OFF WHEN):
DESCRIPTION
OAT exceeds 75°F
OAT exceeds 73°F
OAT exceeds 71°F
OAT exceeds 69°F
OAT exceeds
RA temperature
OAT exceeds return air temperature
minus 2°F
OAT exceeds return air temperature
minus 4°F
OAT exceeds return air temperature
minus 6°F
OAT exceeds 28 Btu/lb of dry air
OAT exceeds 75°F
sensor) is used.
2
level decreases because of the
2
Black Wire
IAQ 2-10 VDC
†
or
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