2- and 4-pipe installations
In 2-pipe installations, the same pipe system is used
for heating and cooling depending on the current
season. Chilled water circulates through the system
during summer and heated water during winter When
RCF-230CD is configured for a 2-pipe system, output
DO4 is used for controlling heating or cooling (depending
on the season (fluid temperature)) via an actuator, a valve
or similar (change-over function).
In 4-pipe installations, there are two separate water
systems for heating and cooling with separate valves. The
thermostat uses two outputs for control of heating and
cooling in sequence.
Automatic cooling/heating change-over
RCF-230CD has an input for change-over which is used
when the thermostat is configured for 2-pipe installations.
It sets output DO4 to operate with heating or cooling
function depending on the fluid temperature (season).
The change-over input can be connected to a
potential-free relay contact or a PT1000-sensor.
The input function for the relay contact can be set to
normally open (NO) or normally closed (NC). If the
change-over input is not used, we recommend that it is
left disconnected and set to NO (factory setting).
When using a sensor, it must be mounted so that it can
measure the temperature on the supply pipe to the coil.
To ensure satisfactory function, the system must also
have continuous primary circuit circulation. Using a
sensor, the output function is set to heating when the
fluid temperature exceeds 28°C and to cooling when the
temperature falls below 16°C.
At heating function “HEAT” is shown in the display and
at cooling function “COOL” is shown.
Occupancy detection for saving energy
By connecting an occupancy detector or a keycard switch
(in hotels) to a digital input, you can alternate between
Comfort and Economy mode. This way, the temperature
is controlled from requirement, making it possible to
save energy while maintaining the temperature at a
comfortable level.
Using occupancy detection, you can delay activation and/
or inactivation of Comfort mode to avoid switching mode
if someone temporarily enters or leaves the room.
A window contact can be connected to either digital
input 1 or universal input 1. The window contact will
set the controller to “Off” mode if a window is opened,
thereby minimising energy consumption.
Operating modes
There are four different operating modes, Comfort,
Economy (Standby), Off and Window. Switching between
these modes is performed locally or via the SCADA
system.
Comfort: is shown in the display and the room is in
use. The temperature is held at the comfort level with
a deadband (DB) between activation of heating and
cooling.
Economy (Standby): “Standby” is shown in the display.
The room is in an energy saving mode and is not used
at the moment. This can for example be during nights,
weekends, evenings etc. or during daytime when there is
no one in the room. The thermostat is prepared to change
operating mode to Comfort if someone enters the room.
Heating and cooling have freely adjustable setpoints.
Off: ”Off” is shown in the display and the backlight
is switched off. The thermostat neither heats or cools
and the fan stops (except if mould protection has been
selected, in which case the fan will keep running). Off
mode is selected by pressing the On/Off button.
Window: is shown in the display and the thermostat is
in off mode and the fan stops (except if mould protection
has been selected, in which case the fan will keep
running).
Fan speed control
The current fan speed is shown in the display and can be
set manually to LowàMediumàHighàAuto by pressing
the fan button. In Auto mode, fan speed is controlled by
the difference between the setpoint and actual value of
the room.
Valve
output
Heating:
X = TON - Room temp.
Cooling:
X = Room temp. - TON
TOFF
TON
0123
1
0
1
2
3
Fan
output
X
When there is no heating or cooling demand in the Auto
position, the fan will run at its lowest setting. This can be
changed to make the fan stop when there is no heating
or cooling demand. The fan is also deactivated when in
modes Off and Window. However, it will continue to run
if mould protection has been configured.
If the fan has been configured to not be affected by
controller output, the ”AUTO” option will not be shown
when pressing the fan button.
Mould protection
When this function has been configured, the fan will
always run at the lowest speed and circulate air in the
room to minimise the risk of mould growth in the fan-coil
unit. The function is deactivated on delivery.
WINTER SUMMER
