Chapter 4 Sequence of operation
56 CNT-SVX05B-EN
Outdoor air damper operation
This sequence applies to both space temperature control and discharge
air temperature control.
The controller operates the modulating outdoor air damper according to
effective occupancy, outdoor air temperature (communicated or hard-
wired sensor), space temperature, effective space temperature setpoint,
discharge air temperature, and discharge air temperature setpoint.
Default minimum damper positions are provided and can be changed
using the Rover service tool for occupied and occupied standby ventila-
tion.
The controller can also receive a communicated outdoor air damper mini-
mum position setpoint. A communicated minimum position setpoint has
priority over all configured minimum position setpoints. When a commu-
nicated minimum position setpoint is not present, the controller uses the
configured minimum setpoints (see Table 20 on page 56).
Table 19. Face-and-bypass damper operation based upon outdoor air
temperature
Outdoor air
temperature
Hydronic heating valve
Face-and-bypass
damper
Outdoor air tempera-
ture is greater than
face-and-bypass heat
modulation setpoint
1
Modulated to maintain
desired setpoint
Full coil face (operation
disabled)
Outdoor air tempera-
ture is less than-face
and-bypass heat modu-
lation setpoint
100% open Modulated to maintain
desired setpoint
(operation enabled)
1 The outdoor air temperature must rise 3°F above the face and bypass heating
enable point before face-and bypass-heating operation is disabled.
Table 20. Determining the outdoor air damper minimum position
setpoint
Occupancy
nviOAMinPos
communicated value
Active outdoor air damper
minimum position setpoint
Unoccupied Present or not present Zero
Occupied
Present Communicated value
Not present Occupied minimum
Occupied bypass
Present Communicated value
Not present Occupied minimum
Occupied standby
Present Communicated value
Not present Occupied standby minimum
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