STRA-14 Room controller. Installation and maintenance manual.
Fläkt Woods
8710 GB 2016.09.08
6 (12)
Specifications are subject of alteration without further notice.
Function button
Shutdown (Off or Unoccupied)
When the Function button is held pressed down for
more than 5 seconds, the controller changes operating
mode to ”Shutdown” that can be ”Off” or ”Unoccupied”,
regardless of the current operating mode. Which
operating mode, Off or Unoccupied, that should be
activated is configured via the display. The factory setting
is activating ”Unoccupied”.
If you press the Function button for less than 5 seconds
when the controller is in Shutdown or preset operating
mode, the controller changes to Boost operating mode.
If you press the button for less than 5 seconds when the
controller is in Boost, it changes operating mode to the
preset operating mode.
After a configurable time in Boost (FS = 60 minutes), the
controller returns to the preset operating mode.
For handling of the Function button in combination with
central control, see the Central control section.
Occupancy detector
For local control of the operating mode regarding
presence in the room, an STRZ-09-1 occupancy detector is
connected.
At occupancy control parameter 45 should be changed
from preset operating mode to 1 = Unoccupied and
parameter 17 changed to 3. Then the function in
illustration below is attained where the controller at
activated occupancy detector shifts to the Occupied
operating mode. When the occupancy detector is
deactivated the controller returns to Unoccupied
operating mode (to attain energy efficiency).
Control states
The controllers can be configured for different control
states/control sequences (Parameter 11, FI = 4 = Heating/
Cooling with VAV-control with forced ventilation):
• Heating (UO1)
• Heating/Heating (UO1/UO2)
• Heating/Cooling
• Heating/Cooling with VAV-control and forced supply
air function (UO1/UO2/UO3)
• Heating/Cooling with VAV-control (UO1/UO2/UO3)
• Cooling (UO1)
• Cooling/Cooling (UO1/UO2)
Heating
In control state Heating, the unit is always a heating
controller and controls according to the heating setpoint
plus/minus the setpoint displacement. The setpoint can be
adjusted in the display.
Heating/Heating
Split output signal
In control state Heating/Heating, the controller is always
a heating controller and controls according to the basic
heating setpoint plus the setpoint displacement. When
the controller output signal reaches 50%, it is divided
between two actuators. 0…48% of the signal is sent to
actuator 1 and 52…100% of the signal is sent to actuator 2.
See the figure below.
Heating/Cooling
In control state Heating/Cooling, the controller functions
as a heating controller when the room temperature is
lower than the basic heating setpoint plus half the neutral
zone. The neutral zone is the difference in temperature
between the heating setpoint and the cooling setpoint.
When the room temperature exceeds this limit, the
controller becomes a cooling controller. There is a
hysteresis of 0.1°C when the controller changes from
heating to cooling controller and vice versa. When the
controller is heating, it regulates according to the basic
heating setpoint plus the setpoint displacement, and
when it is cooling according to the basic cooling setpoint
plus the setpoint adjustment.
