Page 19
Economizer (Damper) (Continued)
Mode Outdoor air is suitable for free cooling when:
TEMP OFFSET Outdoor air temperature (RT17) is less than return air temperature (RT16) by at least the OFFSET value.
TEMP OAT STPT Outdoor air temperature (RT17) is less than the OAT STPT value.
Remote
Either of the TEMP modes can be used when a network OAS signal is provided 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..
ENTH (differential) Outdoor air enthalpy* (A7) is less than return air enthalpy (A62). Enthalpy setpoint potentiometer is set to DIFF
ENTH (setpoint) Outdoor air enthalpy (A7) is less than enthalpy setpoint potentiometer position A, B, C, or D.
GLOBAL
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.)
Enthalpy includes effects of both temperature and humidity.
STEADY YELLOW OUTDOOR
AIR SUITABLE" LED INDICATES
OUTDOOR AIR CAN BE USED
FOR COOLING
ECON DIP SWITCH
M2 UNIT CONTROLLER
0−100%
MINIMUM
POSITION
POTENTIOMETER
Figure 4. Economizer controls
Note−All economizer modes of operation, except DSET, will modulate dampers to 55°F (13°C) discharge air.
ODE DIFFERENTIAL
(Outdoor Enthalpy)
GLO
(Global Enthalpy)
ODE
(Outdoor Enthalpy)
Set to DIF
A
B
C
D
DIF
ENTH SET PNT
A
B
C
D
DIF
Set to A
ENTH SET PNT
TEMP OFFSET,
TEMP OAT STPT, and
Remote MODE.
Figure 5. Economizer free cooling settings
To Next Page
Loading...
Need help?
General
