20
CNT-SVX08F-EN
•
Occupied bypass
Note:
For more detailed information about how the MP501 determines its occupancy mode, refer
to the sections,
“Occupancy Arbitration (Only SCC Mode),” p. 52
.
Occupied Mode
In occupied mode, the controller maintains the zone temperature based on the occupied heating
or cooling setpoints. The controller uses the occupied mode as a default mode if other forms of
occupancy request are not present. The fan runs as configured (continuous or cycling). The PID
loop calculates and controls the outputs whenever the controller is in occupied mode.
Unoccupied Mode
In unoccupied mode, the controller operates to maintain the zone temperature based on the
unoccupied heating or cooling setpoint. The controller always uses the stored default setpoint
values (configurable using the Rover service tool), regardless of the presence of a hardwired or
communicated setpoint value. The PID loop calculates, and the outputs are controlled, whenever
the fan cycles on. Usually, in unoccupied mode, the fan will be off, the PID loop will be inactive,
and the output is at its disabled position.
Occupied Standby Mode
The controller is placed in occupied standby mode only if a communicated occupied request is
combined with an unoccupied request from occupancy binary input. In occupied standby mode,
the controller maintains the zone temperature based on the occupied standby heating or cooling
setpoints. Because the occupied standby setpoints are typically 2°F (1.1°C) higher than the cooling
setpoint and 2°F (1.1°C) lower than the heating setpoint, this mode reduces the demand for heating
and cooling the space. The fan runs as configured (continuous or cycling). The controller always
uses the stored default setpoint values (configurable using the Rover service tool), regardless of
hardwired or communicated setpoint values.
Occupied Bypass Mode
The controller is placed in occupied bypass mode if the controller is operating in the unoccupied
mode and either the timed override on button on the Trane zone sensor is pressed or the controller
receives a communicated occupied bypass signal from a BAS. In occupied bypass mode, the
controller maintains the zone temperature based on the occupied heating or cooling setpoints. The
fan runs as configured (continuous or cycling). The controller remains in occupied bypass mode
until either the cancel button is pressed on the Trane zone sensor or the occupied bypass time
(configurable using the Rover service tool) expires. The temperature setpoints can be local
(hardwired), communicated, or stored default values (configurable using the Rover service tool).
Timed Override Control
If the zone sensor has a timed override option (
ON/CANCEL
buttons), pushing the
ON
button
initiates a timed override on request. A timed override on request changes the occupancy mode
from unoccupied mode to occupied bypass mode. In occupied bypass mode, the controller
controls the zone temperature based on the occupied heating or cooling setpoints. The occupied
bypass time, which resides in the MP501 and defines the duration of the override, is configurable
using the Rover service tool from 0 to 240 minutes (default value of 120 minutes). When the
occupied bypass time expires, the unit transitions from occupied bypass mode to unoccupied
mode.
Pushing the
CANCEL
button initiates a timed override cancel request. A timed override cancel
request will end the timed override before the occupied bypass time has expired and will transition
the unit from occupied bypass mode to unoccupied mode.
If the controller is in any mode other than unoccupied when the
ON
button is pressed, the controller
still starts the occupied bypass timer without changing the mode to occupied bypass. If the
controller is placed in unoccupied mode before the occupied bypass timer expires, the controller
