Parameter Adjustments - Lennox Prodigy 2.0 Application Manual

7.11.4. Parameter Adjustments

Default indoor air quality economizer operation is based on common or average applications. Adjustments may be made to
the indoor air quality parameters to alter operation or meet required specifications. Use the user interface to change
Parameter 117 through 119. Go to SETTINGS > RTU OPTIONS > EDIT PARAMETER
Select a demand control ventilation mode with Parameter 134. Modes 3 and 4 will bring on the unit blower when demand
control ventilation calls for maximum damper open, and returns to auto-blower when demand control ventilation damper
returns to 0. The other modes only operate when the unit blower is on, but will not bring it on themselves.
Some applications require a different carbon dioxide set point range than default settings. Damper "start open" (Parameter
118 and "full open" (Parameter 119) carbon dioxide set points may be adjusted from 0 to 2000 ppm. Use the following
formula to determine damper travel.
NOTE - When changing carbon dioxide set point range, "start open" set point should be less than "full‐open" set point.
% Damper Travel = carbon dioxide ppm - Start Open ppm X Max Open (Parameter 117) Full Open - Start Open
Example: An application requires the dampers open at 800 CO
dioxide level in the space reads 1000 ppm, calculate the damper percent open as follows.
% Damper Travel =
Control Parameter
No Screen Name
117 DCV MAX DAMPER OPEN
118 DCV DAMP START OPEN
119 DCV DAMP FULL OPEN
120 DCV HI TMP OV FL CL
121 DCV HI TMP OV ST CL
122 DCV LO TMP OV FL CL
Full Open -
1000 - 800 or 200 or .5
1200 - 800 400
Table 32. Demand Control Ventilation Parameters
Parameter Short
Description
Min.
Demand Control
Ventilation Maximum
0
Damper Open
Demand Control
Ventilation Damper 0
Start Open
Demand Control
Ventilation Maximum
0
Damper Full Open
Set Point
Demand Control
Ventilation Outdoor
Air Control Hi -31.0
Temperature Override
Full Closed
Demand Control
Ventilation Outdoor
Air Control Hi -31.0
Temperature Override
Start Closing
Demand Control
Ventilation Outdoor
Air Control Low -31.0
Temperature Override
Full Closed
Start Open
ppm and reach full open at 1200. If the carbon
2
= 0.5 x 100 = 50%
Control Value
Default Max.
100 100
700 2000
1200 2000
105.0 132.0
75.0 132.0
10.0 132.0
Page 41
Units Description
Maximum allowed demand con­
trol ventilation damper open posi­
%
tion.
•
Damper "start open" CO
set point for Demand Control
Ventilation.
PPM
•
Level where
damper begins to open.
•
Damper "full open" CO
point for Demand Control
Ventilation.
PPM
•
Level where
damper is opened to maxim­
um.
High outdoor air temp. where
°F fresh air damper is closed to
minimum position.
High outdoor air temperature
°F where fresh air damper begins to
close.
Low outdoor air temperature
where fresh air damper is closed
°F
to minimum position
2
fresh air
set
2
fresh air