Trane Tracer UC400 - ASHRAE Cycle 1 Conformance; ASHRAE Cycle 2 Conformance

46
BAS-SVX48H-EN
configured minimum position for low fan speed whenever the fan is running at low speed,
regardless of the occupancy state. Refer to the following tables for more information about how
the unit determines the position of the modulating outdoor air damper.
Table 9. 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. OA Temp and Damper Position Relationship
Modulating Outdoor Air Damper Position
Outdoor Air
Temperature
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 (Refer to the
section, Economizing
(Free Cooling), p. 46).
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;
otherwise
closed.
Outdoor air temperature
present and economizing
not possible (Refer to the
section, Economizing
(Free Cooling), p. 46).
Open to occupied
minimum position.
Open to occupied
standby minimum
position.
Closed.
ASHRAE Cycle 1 Conformance
ASHRAE Cycle 1 admits 100% outdoor air at all times except during a warm-up cycle. To
configure the UC400 Controller for ASHRAE Cycle 1 conformance, the occupied outdoor air
damper minimum position is set to 100% open. During occupied periods, the modulating damper
opens 100%. If the space temperature drops 3ºF below the active setpoint, the UC400 Controller
closes the outdoor air damper regardless of the active minimum damper position. The controller
moves the modulating valve to the desired positions based on heating or cooling requirements.
ASHRAE Cycle 2 Conformance
The UC400 Controller conforms to the ASHRAE Cycle 2 by allowing the modulating outdoor
damper to completely close when the space temperature drops 3°F, or more, below the effective
setpoint. When the space temperature rises within 2°F of the effective setpoint, the damper is
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