Dcv Set And Max Settings - Lennox KGB Series Unit Information

1- Set thermostat to occupied mode if the feature is avail­
able. Make sure jumper is in place between TB1 termi­
nals R and OC if using a thermostat which does not
have the feature.
2- Rotate MIN POS SET potentiometer to approximate
desired fresh air percentage.
Note - Damper minimum position can be set lower than tra­
ditional minimum air requirements when an IAQ sensor is
specified. Dampers will open to DCV MAX setting (if CO2 is
above setpoint) to meet traditional ventilation require­
ments.
3- Measure outdoor air temperature. Mark the point on
the bottom line of chart 1 and label the point "A" (40_F,
4_C shown).
4- Measure return air temperature. Mark that point on the
top line of chart 1 and label the point "B" (74_F, 23_C
shown).
5- Measure mixed air (outdoor and return air) tempera­
ture. Mark that point on the top line of chart 1 and label
point "C" (70_F, 21_C shown).
6- Draw a straight line between points A and B.
7- Draw a vertical line through point C.
_F
-20
_C
-29
0
10
20
30
40
50
60
70
80
90
100
_F
-20
_C
-29
CHART 1
CALCULATE MINIMUM FRESH AIR PERCENTAGE
MIXED AND RETURN AIR TEMPERATURE
-10 0 10 20 30 40
-23 -18 -12 -7 -1
A
-10 0 10 20 30 40
-23 -18 -12 -7 -1
OUTDOOR AIR TEMPERATURE
8- Draw a horizontal line where the two lines meet. Read
the percent of fresh air intake on the side.
9- If fresh air percentage is less than desired, adjust MIN
POS SET potentiometer higher. If fresh air percentage
is more than desired, adjust MIN POS SET poten­
tiometer lower. Repeat steps 3 through 8 until calcula­
tion reads desired fresh air percentage.

DCV Set and Max Settings

Adjust settings when an optional IAQ sensor is installed.
The DCV SET potentiometer is factory-set at approxi­
mately 50% of the potentiometer range. Using a standard
1-2000ppm CO sensor, dampers will start to open when
2
the IAQ sensor reads approximately 1000ppm. Adjust
the DCV SET potentiometer to the approximate setting
specified by the controls contractor. Refer to figure 28.
The DCV MAX potentiometer is factory-set at approxi­
mately 50% of the potentiometer range or 6VDC.
Dampers will open approximately half way when CO
es above setpoint. Adjust the DCV MAX potentiometer to
the approximate setting specified by the controls con­
tractor. Refer to figure 28.
Note - DCV Max must be set higher than economizer mini­
mum position setting for proper demand control ventilation.
50 60 70 80 90
4 10 16 21 27 32
C B
50 60 70 80 90
4 10 16 21 27 32
Page 66
_F
100
_C
38
0
10
20
30
40
50
60
70
80
90
100
_F
100
_C
38
ris­
2