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Variable air volume controllers
Control states
RC has control state:
• Heating and cooling in sequence
The change-over function can be activated, see below.
Operating modes
There are three different operating modes: Stand-by,
Occupied and Bypass. Occupied is the preset operating
mode. It can be changed to Stand-by with a dipswitch.
The operating modes can be activated via an occupancy
detector.
Stand-by :
The room is in an energy save mode and
is not used at the moment. This can for example be
during nights, weekends, evenings etc. The controller
is prepared to change operating mode to Occupied if
someone enters the room. Both heating and cooling are
disconnected within a temperature interval around the
applicable setpoint (heating setpoint value=-3°C, cooling
setpoint=+3°C).
Occupied :
The room is in use and is therefore in a
comfort mode. The controller regulates the temperature
around a heating setpoint (22°C) and a cooling setpoint
(24°C).
Bypass:
The temperature in the room is controlled in the
same way as in operating mode Occupied. The output
for forced ventilation is also active. Bypass is useful for
example in conference rooms, where many people are
present at the same time for a certain period of time.
After 10 minutes absence, the controller will
automatically return to the preset operating mode
(Occupied or Stand-by).
Occupancy detector
By connecting an occupancy detector, RC can switch
between Bypass and the preset operating mode
(Occupied or Stand-by). The temperature is then
controlled according to requirement, which saves energy
and keeps the temperature at a comfortable level.
Change-over function
RC has an input for change-over that automatically resets
output UO1 to operate with heating or cooling function.
The input can be connected to sensors of type PT1000
and have the sensor mounted so that it senses the
temperature on the supply pipe to the coil.
When the temperature exceeds 22°C, the output function
is set to heating and when the temperature drops below
18°C, the output is set to cooling.
As an alternative, a potential-free contact can be used.
When the contact is open the controller works with the
heating function and when it is closed, with the cooling
function.
To ensure satisfactory functioning using sensor, the
system must have continuous primary circuit circulation.
When the change-over function is not used, the input
must be left disconnected.
Setpoint
In Occupied mode, the controller operates from a heating
setpoint (22°C) or a cooling setpoint (24°C) that can be
changed locally using dipswitches.
The setpoint can be adjusted up and down
(±3°C) with the knob on the front of the controller.
Switching between heating and cooling setpoints is done
automatically in the controller depending on the heating
and cooling requirement.
Built-in safety functions
RC has an input for a condensation detector which
prevents condensation. The controller also has frost
protection. It prevents frost damages by by ensuring that
the room temperature does not drop below 8°C when the
controller is in Off-mode (caused by open window).
Indications
The controller has an LED shaped like a thermometer on
the front. A red indication is shown when heating control
is functional and a blue indication when cooling control is
active. No LED indication shows that neither heating nor
cooling control is active.
Actuator exercise
All actuators are exercised. The exercise takes place
at a 23 hours interval. An opening signal is sent to
the actuator for as long time as the run time has been
configured. Then a closing signal is sent for as long time
and the exercise is finished.
Application example
Window
contact
IR
Temp
Condensation detector
