Occupied Standby Mode - Trane Tracer AH540 Setup And Operation

Chapter 4 Sequence of operation
42
Space temperature control: Unoccupied mode
In unoccupied mode, if configured for space temperature control, the sup-
ply fan is Off whenever the space temperature is between the unoccupied
heating and cooling setpoints. If the space temperature rises above the
unoccupied cooling setpoint the Tracer AH540/541 turns On the supply
fan and provides cooling at the unoccupied cooling setpoint.
If the space temperature drops below the unoccupied heating setpoint the
controller turns On the supply fan and provides heating at the unoccu-
pied heating setpoint. See Table 43 on page 78.
Discharge air temperature control: Unoccupied mode
In unoccupied mode, if configured for discharge air temperature control,
the controller must have either a hard-wired or communicated space tem-
perature input from the Tracer Summit building automation system.
In unoccupied mode, the supply fan is Off whenever the space tempera-
ture is between the unoccupied heating and cooling setpoints. If the space
temperature rises above the unoccupied cooling setpoint the Tracer
AH540/541 turns On the supply fan and provides cooling at the discharge
air cooling setpoint.
If the space temperature drops below the unoccupied heating setpoint the
controller turns On the supply fan and provides heating at the discharge
air heating setpoint. See Table 44 on page 79.
Note that primary heating or cooling capacity is defined by unit type and
whether heating or cooling is enabled or disabled. For example, if the
economizer is enabled and possible, it will be the primary cooling capac-
ity. If hydronic heating is possible, it will be the primary heating capacity.

Occupied standby mode

If configured for space temperature control, the controller uses the occu-
pied standby mode to reduce heating and cooling demands during occu-
pied hours when a space is vacant or unoccupied. For example, the
controller may use occupied standby mode for a classroom while the stu-
dents are out of the room.In the occupied standby mode, the controller
uses the occupied standby cooling and heating setpoints. Because the
occupied standby setpoints typically cover a wider range than the occu-
pied setpoints, the Tracer AH540/541 controller reduces the demand for
heating and cooling the space. Also, the outdoor air economizer damper
uses the economizer standby minimum position to reduce the heating and
cooling demands.
Occupied standby is a mode in which the controller has received an occu-
pied request from Tracer Summit, but has also received a local unoccu-
pied binary input IN9 signal. For example, an unoccupied conference
room (as sensed by a local occupancy sensor) in an occupied building (as
commanded by a Tracer Summit system) is in occupied standby mode.
When the conference room becomes occupied with people, the local occu-
pancy sensor changes the controller mode to occupied.
CNT-SVX05B-EN