Economizer; General; Damper Operations During Free Cooling - Lennox Prodigy 2.0 Application Manual

7. Economizer

7.1.

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.
7.2. 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.
Note: Available menu options are dependent on hardware configuration.
Level 2 Level 3
RTU OPTION DAMPER
7.3. 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.
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.
Table 30 . Menu Interface (Level 1 - SETTINGS)
Level 4
ECONOMIZER ENTHALPY OFFSET = X MA
ECONOMIZER TEMP ECON TYPE = TEMPERATURE OFFSET OR TEMPERATURE SETPT
ECONOMIZER OAT SETPOINT = XX.X F
FREE COOLING SUPPLY AIR SETPOINT = XX F
MIN DAMPER POSITION BLOWER ON HIGH = X.X %
MIN DAMPER POSITION BLOWER ON LOW = X.X %
DEMAND CONTROL VENT DAMPER START OPEN = XXXX.X PPM
DEMAND CONTROL VENT DAMPER FULL OPEN = XXXX.X PPM
DEMAND CONTROL VENT DAMPER MAX OPENING = XXX.X%
POWER EXHAUST ON BY ECON TRAVEL = XX.X %
FRESH AIR HEATING ENABLE
FAH = YES OR NO
FRESH AIR COOLING ENABLE
AFC = YES OR NO
Page 36
USE THE ADJUST AND SET VALUES ARROWS TO
Level 5
SCROLL UP OR DOWN FOR SELECTION OPTIONS.
FRESH AIR HEATING FAH SETPOINT = XX F
FRESH AIR COOLING AFC SETPOINT = XX F