Lennox KHA SERIES, Manual

Page: 38 / 49

Page 38
−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
B C
_
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
Economizer Operation
The occupied time period is determined by the thermostat
or energy management system.
Outdoor Air Not Suitable:
During the unoccupied time period dampers are closed.
During the occupied time period a cooling demand will
open dampers to minimum position and mechanical cool-
ing functions normally.
During the occupied time period dampers will open to DCV
MAX when IAQ reading is above setpoint (regardless of
thermostat demand or outdoor air suitability).
Outdoor Air Suitable:
See table 13 for economizer operation with a standard two−
stage thermostat.
During the occupied period, dampers will open to DCV
MAX when IAQ reading is above setpoint (regardless of
thermostat demand or outdoor air suitability). DCV MAX
will NOT override damper full−open position. When an R1
mixed air sensor for modulating dampers is installed, DCV
MAX may override damper free cooling position when oc-
cupancy is high and outdoor air temperatures are low. If R1
senses discharge air temperature below 45
_
F (7
_
C),
dampers will move to minimum position until discharge air
temperature rises to 48
_
F (9
_
C).
B−Outdoor Air Dampers
Optional manual and motorized outdoor air dampers pro-
vide fresh outdoor air. The motorized damper assembly
opens to minimum position during the occupied time peri-
od and remains closed during the unoccupied period.
Manual damper assembly is set at installation and re-
mains in that position.
Set damper minimum position in the same manner as
economizer minimum position. Adjust motorized damper
position using the thumbwheel on the damper motor. See
figure 20. Manual damper fresh air intake percentage can
be determined in the same manner.
FIGURE 20
DAMPER MOTOR
THUMBWHEEL