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8. Economizer
8.1. General
The economizer, when configured, controls:
Damper position, which determines how much outdoor air is used to meet free cooling or indoor air quality
requirements, and
Optional power exhaust fans.
On a cooling demand, outdoor air is used for free cooling instead of first-stage compressor(s) when outdoor air is suitable.
8.2. Enabling Economizer and Settings
To enable the economizer if installed go to SETUP > INSTALL and go through the wizard. When reaching Configuration
ID 1, position 2 will need to be set to the applicable type of economizer. Valid types are as indicated below:
M = Motorized Outdoor Air Damper Only
T = Economizer - Temperature (NOTE: Used for both set point and offset temperature control.)
G = Economizer - Global
S = Economizer - Single Enthalpy
D = Economizer - Dual Enthalpy
The following options are available depending on economizer set above. These settings are available through the main
menu at SETUP > TEST & BALANCE > DAMPER.
8.3. Damper Operation During Free Cooling
These are operating profile options for the economizer damper (parameter 164 - ECONOMIZER PROFILE) during free
cooling when any compressor is on and can be selected as follows:
Option 0: Damper continues to modulate while compressors are on, but the effect of mechanical cooling may force the
damper closed to its minimum position. After compressor starts, the free cooling set point is lowered to fixed temperature
setting of 45°F.
NOTE: Option 0 is not supported on Energence Ultra-High Efficiency 3- to 6-ton units.
Option 1: Damper opens to its maxopen position (parameter 131 - FREE CL MAX DAMPER) when any compressors
start.
NOTE: When using Option 1 and after the compressor is stopped, the M3 shall resume damper modulation.
Option 2: Is as follows:
Holdsoff compressor on Y2 call until damper has modulated to maximum position (parameter 131 - FREE CL MAX
DAMPER) for three minutes.
After three minutes, the compressor starts and the free cooling set point is lowered to 45°F. Damper is not locked
at maximum open while compressor is on, but modulates to maintain 45°F discharge air temperature.
When Y2 is satisfied, compressor goes off and free cooling set point is restored to 55°F (parameter 159 - FREE
COOL SUPPLY SP).
Option 3: Same as Option 2, but with a 10 minute delay instead of a three minute delay.
8.4. 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.
8.5. 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 or dual enthalpy modes require additional field-provided sensor(s).
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