Sequence of Operation
50
WSHP-SVX13C-EN
Unoccupied mode
When the controller is in Unoccupied mode, the unit will
attempt to maintain the space temperature at the stored
unoccupied heating or cooling setpoint (configurable
through the BAS or Tracer™ TU).
Occupied Standby mode
The occupied standby mode allows the unit to operate at
a heating or cooling setpoint between the occupied and
unoccupied setpoints (space temperature setpoint ±
standby offset) to help maintain the space while
decreasing energy consumption. Unit operation in this
mode is identical to the occupied mode except for the
different heating and cooling setpoints.
Occupied Bypass mode
The occupied bypass mode is used to transition the unit
from the unoccupied mode to the occupied mode for a
period of time from 0 to 4 hours (configurable through
Tracer™ TU).
The controller can be placed in occupied bypass mode by
either communicating an occupancy request of bypass or
by using the timed override (for example, ON)
functionality of the controller and applicable zone sensors:
Timed override operation
While the unit is operating in unoccupied mode, if the
timed override request button on the zone sensor is
selected for 0.2 to 5 seconds, the unit will recognize this as
a timed override request.This request is always accepted,
but will only transition to occupied bypass mode if the
controller was in unoccupied mode. Once initiated, the
unit will enter occupied bypass mode for the duration of
the occupancy bypass timer (default 120 minutes) or until
the timed override request is cancelled.
While the unit is operating in occupied bypass mode, the
timed override operation can be cancelled by a timed
override cancel request. This request is always accepted,
but the unit will transition back to unoccupied mode only
if the unit is currently operating in occupied bypass mode.
SomeTrane® zone sensors have ON and CANCEL buttons
for timed override operation. Pressing the ON button on
the zone sensor applies a direct short across the space
temperature input, as described above, and when the unit
is in unoccupied mode, initiates the occupied bypass
mode.The CANCEL button applies 1.5 k
across the space
temperature input and is used to return a unit operating in
occupied bypass mode back into Unoccupied mode before
the occupancy bypass timer has expired.
Supply fan mode operation
Variable-speed WSHP units can be set up to have either
cycling or continuous fan mode operation.This feature is
selectable through Tracer™ TU or through a BAS as a
communicated value.The default value for the supply fan
mode is continuous.
Supply fan mode: Cycling
For active cooling, heating operation, the supply fan will
be commanded ON and will ramp up to minimum speed
once the unit determines that there is a request for cooling
or heating operation. Once the control determines that
there is no longer a capacity request, and the compressor
output is OFF, the supply fan will be de-energized once any
supply fan off delays have timed out. During the supply fan
off delay, the supply fan will remain energized for the
predetermined time at the previous unit function’s
minimum speed.
Note:
During heating only, there will be a 30 second
supply fan off delay.
Supply fan mode: ON
For active unit control with the supply fan mode set to
continuous, the unit will energize the supply fan and hold
the fan speed output at the active minimum speed until
there is a request for the fan speed to increase. This will
hold true for all cases except during Unoccupied periods
in which the supply fan mode is forced to operate in
cycling mode.
Zone sensor fan switch
The controller supports a fan switch selection that is
selectable by an applicable zone sensor module.When the
fan switch is set to AUTO, the unit will utilize the configured
supply fan mode (cycling or continuous) for supply fan
output control and will operate heating, cooling, and
dehumidification in order to meet the space demand.
When the fan switch is set to OFF, the unit will enter OFF
mode. All heating and cooling capacity will be de-
energized after the associated minimum on timers expire,
the isolation valve will be de-energized, and the supply fan
will de-energize once any associated off delay timer has
expired; no heating, cooling, or supply fan operation will
be allowed when the fan switch is set to OFF.
If required, the user can enable/disable the zone sensor fan
switch functionality through BAS or the Tracer™ TU
service tool. A fan mode can also be requested through
BAS. If a requested fan mode is requested through BAS,
the local setting is ignored.
