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Chapter 5 Sequence of operations
44 CNT-SVX07C-EN
low-speed fan operation. A controller can also receive a BAS-communi-
cated outdoor air damper minimum position.
A BAS-communicated minimum position setpoint has priority over all
locally configured setpoints. When a communicated minimum position
setpoint is not present, the controller uses the configured minimum posi-
tion for low fan speed whenever the fan is running at low speed, regard-
less of the occupancy state. See Table 9 and Table 10 for more information
about how the controller determines the position of the modulating out-
door air damper.
Table 9. Modulating outdoor air damper position setpoint determination
Occupancy
BAS-communicated
setpoint
Fan speed Active minimum setpoint
Unoccupied Any value Any value 0% (closed)
Occupied
Occupied bypass
Occupied standby
Valid Any value BAS-communicated
Occupied
Occupied bypass
Occupied standby
Invalid Low Occupied low fan minimum
Occupied
Occupied bypass
Invalid Medium/high Occupied minimum
Occupied standby Invalid Medium/high Occupied standby minimum
Table 10. Relationship between outdoor temperature sensors and damper position
Outdoor air temperature
Modulating outdoor air damper position
Occupied or occupied
bypass
Occupied standby Unoccupied
No or invalid outdoor air
temperature
Open to occupied
minimum position
Open to occupied standby
minimum position
Closed
Failed outdoor air sensor Open to occupied
minimum position
Open to occupied standby
minimum position
Closed
Outdoor air temperature
present and economizing
possible
1
Economizing; damper
controlled between
occupied minimum
position and 100%
Economizing; damper
controlled between
occupied standby
minimum position and
100%
Open and economizing
during unit operation; oth-
erwise closed
Outdoor air temperature
present and economizing
not possible
1
Open to occupied mini-
mum position
Open to occupied standby
minimum position
Closed
1
For an explanation of the economizing feature, see “Economizing (free cooling)” on page 45.