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7.4. Free Cooling Compressor Lockout Mode and Low Ambient Set Point
Go to SETTINGS > RTU OPTION > EDIT PARAMETER = 285 (FRCL COMP LCKOUT MD). Default value is 2. Range
is 0 to 2.
0 = Disable Compressor Lockout
1 = Lockout Compressor if outdoor air is suitable regardless of outdoor air temperature.
2 = Lockout Compressor if outdoor air temperature is below Parameter 108 setting and Outdoor Air is Suitable (Default).
Go to SETTINGS > RTU OPTION > EDIT PARAMETER = 108 (FREE LO AMB LCKT SP). Default value is 55.0°F.
Range is 45.0 to 80.0°F.
7.5. Outdoor Air Suitable for Free Cooling
The M3 Unit Controller displays the outdoor air suitability information on the status screen.
The appropriate sensors are provided when the economizer is factory-configured. When the economizer is field-installed
and configured, the single/dual enthalpy mode requires additional field-provided sensor(s).
7.6. Enthalpy Set Point
This setting pertains to the single enthalpy free cooling mode only. The M3 Unit Controller will enable free cooling when
outdoor air enthalpy (A7) is less than the enthalpy set point (Parameter 162 - ECON FREECL ENTH SP). Figure 8 shows
the approximate enthalpy sensor output at various temperatures and percentage of relative humidity.
40°F 50°F 60°F 70°F 80°F 90°F 100°F
30
20
10
40
50
60
70
80
90
100
Figure 8. Enthalpy Sensor Output Current Honeywell C7400
7.7. Free Cooling Damper Maximum Position
Damper Maximum position for free cooling is by default set to 100%. To modify this settings, use the following path:
SETTINGS > RTU OPTION > EDIT PARAMETER - 131 (FREE CL MAX DAMPER)
7.8. Minimum Damper Position
Use the following menu path to modified the minimum damper positions for both high and low operations.
SETUP > TEST & BALANCE > DAMPER > MIN DAMPER POSITION BLOWER ON HIGH = .%
SETUP > TEST & BALANCE > DAMPER > MIN DAMPER POSITION BLOWER ON LOW = .%
7.9. Motorized Outdoor Air Damper
Set damper position according to “Minimum Damper Position” section 7.8. For normal operation, make sure the motorized
outdoor air damper is set correctly in Configuration ID 1, position 2 needs to be set to M. The damper will open to the
specified position during the occupied time period and close during the unoccupied time period.
NOTE - When equipped with Motorized Outdoor damper Air Damper, Prodigy 2.0 provides only Demand Control
Ventilation. Free Cooling/Economizer function is not available.
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