Lennox KGB Series User Manual

Page 66
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.
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
2
sensor, dampers will start to open when
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
2
ris
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.
-20
-29
-10
-23
0
-18
10
-12
20
-7
30
-1
40
4
50
10
60
16
70
21
80
27
90
32
100
38
0
10
30
40
50
60
70
80
90
100
20
OUTDOOR AIR TEMPERATURE
0
10
30
40
50
60
70
80
90
100
20
MIXED AND RETURN AIR TEMPERATURE
CHART 1
CALCULATE MINIMUM FRESH AIR PERCENTAGE
A
BC
_F
_C
_F
_C
-20
-29
-10
-23
0
-18
10
-12
20
-7
30
-1
40
4
50
10
60
16
70
21
80
27
90
32
100
38
_F
_C
_F
_C

Lennox KGB Series Specifications

General

Brand	Lennox
Model	KGB Series
Category	Heat Pump
Language	English