STRA-24 Installation and commissioning manual
Fläkt Woods 9585 GB 2015.12.16 5 (12) Specifications are subject of alteration without further notice.
Operating modes
STRA-24 has five different operating modes. Through
the Function button you are able to switch between three
of them. These are set through the parameter menu
(parameter 45) in the display. Occupied is the preset
mode.
Off
Operating mode Off means that the controller is switched
off, i.e. heating and cooling are disabled. However,
the temperature may not drop below the set minimum
temperature (parameter 6, FS = 8°C). If it does, the
controller will start heating. The background lighting
on the display is not lit, and only OFF is shown in the
display.
Airflow will be a non-presences airflow, V0, which is set
on the actuator.
Unoccupied (Energy Saving Mode)
Operating mode Unoccupied is an energy saving mode.
It means that the room where the controller is placed
is not used for an extended period of time, for example
during evenings, nights or weekends. The controller is
prepared to change the operating mode to Occupied if
someone enters the room (occupancy detector is needed
to use this feature). Both heating and cooling are disabled
within a temperature interval with configurable min/max
temperatures (parameter 4 respectively 5, FS min = 19°C,
max = 27°C).
Airflow will be a non-presences airflow, V0, which is set
on the actuator. However if the cooling water valve is
fully open and there is still a need for more cooling, the
airflow will increase to Vmin and then linearly up to Vmax
if required.
The background lighting on the display is not lit, but the
current room temperature (or setpoint value depending
on the configuration) is shown in the display. OFF is
shown in the display for this operating mode as well.
Standby (Energy Saving Mode)
Operating mode Standby means that the room is in an
energy saving mode and is not used at the moment.
This can be during evenings, nights, weekends etc. The
room temperature is controlled around the applicable
heating and cooling setpoint values, with an extended
temperature interval (FS = +/-3°C).
Airflow will be a non-presences airflow, V0, which is set
on the actuator. However if the cooling water valve is
fully open and there is still a need for more cooling, the
airflow will increase to Vmin and then linearly up to Vmax
if required.
For example, if the heating setpoint value is 22°C and the
cooling setpoint value is 24°C, the controller will allow
the temperature in the room to be between 19°C and 27°C.
Local adjustment of setpoint value via the display on
STRA-24.
The background lighting on the display is lit (dimmed)
and STANDBY with the current room temperature (or
setpoint value depending on the configuration) are
shown in the display. For more information , see Section
Occupancy detector, page 6.
Occupied (Normal Mode)
Operating mode Occupied means that the room is in
use and is therefore in a comfort mode. The controller
regulates the room temperature around a heating
setpoint value and a cooling setpoint value (parameter 1
respectively 2, FS heating setpoint value = 22°C, cooling
setpoint value = 24°C). Airflow will be on a presences
airflow, Vmin, which is set on the actuator. However if the
cooling water valve is fully open and there is still a need
for more cooling, the airflow will increase linearly from
Vmin up to Vmax if required. The setpoint values can also
be adjusted +/-3°C locally via the display, or via a central
command.
The background lighting on the display is lit (dimmed),
and the occupancy indication is shown (see Section
Display, page 3). The current room temperature (or
setpoint value depending on the configuration) is shown
in the display.
Bypass (Boost Mode)
Operating mode Bypass means that the controller controls
the room temperature in the same way as in operating
mode Occupied. For the chilled beam this activates the
output for forced ventilation and the air flow goes to Vmax
airflow which is set on the actuator. After a configurable
time (parameter 12, FS = 60 minutes) the controller
automatically returns to the preset operating mode. Boost
is normally activated when the Occupancy button is
pressed or a central command. The operating mode is
useful for example in conference rooms where many
people are present at the same time during a limited
period of time.
The background lighting on the display is lit (dimmed).
The occupancy indication and the symbol for forced
ventilation are shown (see Section Display, page 3). The
current room temperature (or setpoint value depending
on the configuration) is shown in the display.
Activation of operating modes
Preset operating mode
Occupied is the preset operating mode. Configuration of
desired operating mode is done in the parameter menu
on the display (parameter 45). The operating mode is
changed at following events:
• When the Occupancy button is pressed.
• Activation/deactivation of an occupancy detector.
• Via central control, for example central time control,
central booking system etc.
