Page 60
TABLE 24
ECONOMIZER MODES AND SETPOINT
Free
Cooling
Mode
Free Cooling
Setpoint
Field-
Provided
Sensors
Dampers will modulate to 55°F (default, parameter 159)
discharge air (RT6) when outdoor air is suitable:
Input Ranges
TEMP OFFSET None Needed
Outdoor air temperature (RT17) is less than return air temperature (RT16)
by at least the OFFSET value (10
°F default; parameter 161).
0-40°F
TEMP OAT STPT None Needed
Outdoor air temperature (RT17) is less than the OAT STPT value (75°F
default; parameter 160).
41-75°F
Remote Remote
Energy
Management
System**
Either of the TEMP modes can be used when a network OAS signal is pro
vided by an energy management or building control system, via BACnet,
LonTalk, or L Connection. The network can command OAS, NOT OAS, or
AUTO. AUTO returns to local control of OAS, which is the selected TEMP
mode.
NA
ENTH DIFF OFFSET (Two) C7400
Outdoor air enthalpy* (A7) is less than return air enthalpy (A62) by at least
the OFFSET value (1mA = 2
°F default; parameter 163).
0mA-4mA
ENTH ODE STPT C7400
Outdoor air enthalpy (A7) is less than free cooling setpoint (12mA = 75°F
default, parameter 162).
12-19mA
GLOBAL GLOBAL
24VAC Input
Signal
Global input is energized by (P297-9). This setting is also used for outdoor
air damper applications. Global input also brings on the blower. (This mode
is NOT used when OAS signal is provided via network connection. GLO is
only used when a 24VAC signal is used to energize the P297-9 GLO input.)
NA
*Enthalpy includes effects of both temperature and humidity.
**Energy management systems may require additional field-provided sensors; refer to manufacturer's instructions.
FIGURE 29
ACCESSORY
PANEL MULLION
DIVIDER PANEL
(Attach with two
provided screws)
BOTTOM OF
COMPRESSOR
SECTION
FLANGED
RETURN AIR
OPENING
ECONOMIZER
ECONOMIZER
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