CNT-SVX17G-EN 63
Sequence of Operations
Unoccupied Space Temperature Control
When no space temperature is present, the controller does not run heating or cooling
capacity in unoccupied. Ventilation requirements are assumed to be zero. The controller
enters this mode from a communicated command or from a local occupancy sensor.
Table 41 shows unoccupied space temperature control.
Table 41.Unoccupied space temperature control
Primary air
temperature
Space temperature
Primary airflow
control
Fan control Reheat control
Cold air in duct:
Primary air
te
mperature <
configured auto
changeover setpoint
minus 10°F
< than or equal to active
heating setpoint minus 1.5°F
Close air valve Series On
Parallel On
Reheat On 100%
Close air valve Series Off
Parallel Off
Not present
Local heat min Not present Reheat On 100%
> Active heating setpoint plus
1.5
°
F
Close air valve Series Off
Parallel Off
Reheat Off
< Active cooling setpoint minus
1.5°F
Close air valve Series Off
Parallel Off
Reheat Off
> Active cooling setpoint plus
1.5°
F
Max flow setpoint Series On
Parallel Off
Reheat Off
Warm air in duct:
Configured auto
ch
angeove
r setpoint <
primary air
temperature <
configured reheat
enable setpoint minus
5°F
< Active heating setpoint
minus 1.5°F
Max heat flow
setpoint
Series On
Parallel On
Reheat On 100%
< Active heating setpoint
minus 1.5°F
Max heat flow
setpoint
Series On
Parallel Off
Not present
> Active heating setpoint plus
1.5°
F
Close air valve Series Off
Parallel Off
Reheat Off
< Active cooling setpoint minus
1.5°F
Close air valve Series Off
Parallel Off
Reheat Off
> Active cooling setpoint plus
1.5°
F
Close air valve Series Off
Parallel Off
Reheat Off
Hot air in duct:
Primary air
t
e
mperature >
configured reheat
enable setpoint
< Active heating setpoint
minus 1.5°F
Max heat flow
setpoint
Series On
Parallel Off
Reheat Off
> Active heating setpoint plus
1.5°
F
Close air valve Series Off
Parallel Off
Reheat Off
< Active cooling setpoint minus
1.5°F
Close air valve Series Off
Parallel Off
Reheat Off
> Active cooling setpoint plus
1.5°
F
Close air valve Series Off
Parallel Off
Reheat Off
A VAV unit turns the series fan to ON, if present, when capacity is being run. A parallel
fan turns ON only if reheat is ON. The air valve is closed when the space temperature is
between the unoccupied setpoints. When there is no more need for heat capacity, the
heat capacity is turned OFF. There is a 15-second fan OFf delay. See the fan OFF delay
section in this specification for more details.
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